JP7413020B2 - Alkali metal-sulfur secondary battery including protected sulfur cathode and manufacturing method - Google Patents

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. patent application Ser. No. 15/440,151, both filed February 23, 2017, which is hereby incorporated by reference.

The present invention provides unique cathode compositions and structures in secondary or rechargeable alkali metal-sulfur batteries, including lithium-sulfur batteries, sodium-sulfur batteries, and potassium-sulfur batteries. Lithium-sulfur batteries include lithium metal-sulfur batteries (with lithium metal as the anode active material and sulfur as the cathode active material) and lithium ion-sulfur batteries (e.g., with Si or graphite as the anode active material and cathode active material). sulfur). Sodium-sulfur batteries include sodium metal-sulfur batteries (e.g., having sodium metal as the anode active material and sulfur as the cathode active material) and sodium ion-sulfur batteries (e.g., hard carbon as the anode active material and sulfur as the cathode active material). ) may be included.

Rechargeable lithium ion (Li ion) and lithium metal batteries (including Li-sulfur and Li metal-air batteries) are used in electric vehicles (EVs), hybrid electric vehicles (HEVs), and portable electronic devices such as laptop computers and It is considered a promising power source for mobile phones. Lithium as a metallic element has the highest capacity ₍ 3,861mAh/g). Therefore, Li metal batteries generally have a significantly higher energy density than lithium ion batteries.

Historically, rechargeable lithium metal batteries have used materials with relatively high specific capacities such as _TiS2 , _MoS2 , _MnO2 , _CoO2 , and _V2O5 as cathode active materials combined with a lithium metal anode _. Manufactured using non-lithiated compounds. When the cell was discharged, lithium ions were transferred from the lithium metal anode through the electrolyte to the cathode, lithiation of the cathode. Unfortunately, upon repeated charging and discharging, the lithium metal formed dendrites at the anode that eventually grew through the separator, causing an internal short circuit and an explosion. As a result of a series of accidents related to this problem, production of these types of secondary batteries was discontinued in the early 1990s and replaced by lithium ion batteries.

In lithium ion batteries, a sheet or film of pure lithium metal was replaced by a carbonaceous material as the anode. The carbonaceous material absorbs lithium (eg, by intercalation of lithium ions or atoms between graphene planes) and desorbs lithium ions during the respective recharge and discharge phases of lithium ion battery operation. The carbonaceous material may primarily contain graphite that can be intercalated with lithium, and the resulting graphite intercalation compound can be represented as Li _x C ₆ , where x is typically is less than 1.

Lithium-ion (Li-ion) batteries are a promising energy storage device for electric vehicles, but current state-of-the-art Li-ion batteries have not yet met cost and performance goals. Li-ion cells typically use lithium transition metal oxides or phosphates as the positive electrode (cathode) to de/re-intercalate Li+ at high potentials relative to the carbon negative electrode (anode). The specific capacity of lithium transition metal oxide or phosphate-based cathode active materials is typically in the range of 140-170 mAh/g. As a result, the specific energy of commercially available Li-ion cells is typically in the range of 120-220 Wh/kg, most typically 150-180 Wh/kg. These specific energy values are two to three times lower than would be required for battery-powered electric vehicles to gain widespread acceptance.

With the rapid development of hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (HEVs), and all-battery electric vehicles (EVs), significantly higher specific energy, higher energy density, higher rate performance, longer cycle life, and There is an urgent need for anode and cathode materials that provide safe rechargeable batteries. One of the most promising energy storage devices is the lithium-sulfur (Li-S) cell. This is because the theoretical capacity of Li is 3,861 mAh/g and the theoretical capacity of S is 1,675 mAh/g. In its simplest form, a Li-S cell consists of elemental sulfur as the positive electrode and lithium as the negative electrode. Lithium-sulfur cells operate with a redox couple represented by the reaction S ₈ +16Li⇔8Li ₂ S near 2.2V for Li ⁺ /Li ⁰ . This electrochemical potential is approximately 2/3 of the potential exhibited by a conventional positive electrode (eg, LiMnO ₄ ). However, this drawback is offset by the very high theoretical capacities of both Li and S. Therefore, compared to traditional intercalation-based Li-ion batteries, Li-S cells have the potential to provide significantly higher energy density (capacity and voltage product). Assuming complete reaction to Li ₂ S, the energy density values can approach 2,500 Wh/kg and 2,800 Wh/L based on the total weight or volume of Li and S, respectively. Based on total cell weight or volume, the energy density can reach approximately 1,000 Wh/kg and 1,100 Wh/L, respectively. However, current Li-sulfur cells reported by industry leaders in sulfur cathode technology have maximum cell specific energies of 250-400 Wh/kg (based on total cell weight), which is lower than the possible values. is also quite low.

In summary, despite the considerable advantages, Li-S cells suffer from some major technical problems, as shown schematically in Figure 2. impeding widespread commercialization.
(1) Conventional lithium metal cells still have problems with dendrite formation and related internal short circuits.
(2) Sulfur or a sulfur-containing organic compound has high electrical and ionic insulation properties. To enable reversible electrochemical reactions at high current densities or charge/discharge rates, the sulfur must remain in close contact with the conductive additive. Various carbon-sulfur composites have been utilized for this purpose, but with limited success due to the limited scale of the contact area. Typical capacities reported are 300-550 mAh/g (based on cathode carbon-sulfur composite weight) at moderate rates.
(3) The cell tends to exhibit significant capacity decay during discharge-charge cycles. This is mainly due to the high solubility of lithium polysulfide anions, which are formed as reaction intermediates in both the discharging and charging processes, in the polar organic solvents used in the electrolyte. During cycling, lithium polysulfide anions may migrate through the separator to the Li negative electrode where they are reduced to solid precipitates (Li ₂ S ₂ and/or Li ₂ S), causing active mass loss. Furthermore, solid products deposited on the surface of the positive electrode during discharge become electrochemically irreversible, which also contributes to active mass loss.
(4) More generally, a major drawback of cells containing cathodes containing elemental sulfur, organic sulfur, and carbon-sulfur materials is that soluble sulfides, polysulfides, Concerning dissolution and excessive out-diffusion of organosulfides, carbon sulfides, and/or polysulfides (hereinafter referred to as anionic reduction products). This phenomenon is commonly called the shuttle effect. This process creates several problems, including: high self-discharge rates, loss of cathode capacity, corrosion of the current collector and electrical leads resulting in loss of electrical contact to the active cell components, and corrosion of the anode. Fouling of the anode surface leading to malfunction and clogging of the pores of the cell membrane separator leading to loss of ion transport and a large increase in internal resistance within the cell.

In response to these challenges, new electrolytes, protective films for lithium anodes, and solid electrolytes have been developed. Several interesting cathode developments have been reported recently, including lithium polysulfide. However, their performance has not yet reached the level required for practical use.

For example, Ji et al. reported that a cathode based on nanostructured sulfur/mesoporous carbon material can largely overcome these challenges, exhibiting stable and high reversible capacity, and excellent rate characteristics and cycling efficiency [Xiulei Ji , Kyu Tae Lee, & Linda F. Nazar, “A highly ordered nanostructured carbon-sulfur cathode for lithium-sulfur batteries,” Nature Materials 8, 500-506 (2 009)]. However, the fabrication of the proposed highly ordered mesoporous carbon structures requires a tedious and expensive template-assisted process. It is also difficult to load high proportions of sulfur into these mesoscale pores using physical vapor deposition or solution precipitation methods.

Zhang et al. (US Patent Publication No. 2014/0234702; August 21, 2014) utilize a chemical reaction method to deposit fine S particles on the surface of isolated graphene oxide (GO) sheets. However, this method is unable to create a high proportion of S particles (ie, typically less than 66% S in GO-S nanocomposite compositions) on the GO surface. The resulting Li-S cells also have poor rate performance; for example, a specific capacity of 1,100 mAh/g (based on S weight) at a rate of 0.02 C but <450 mAh/g at a rate of 1.0 C. will be lowered to Note that the highest achievable specific capacity of 1,100 mAh/g indicates a sulfur utilization efficiency of 1,100/1,675 = 65.7% even at such low charge/discharge rates (0. 02C means to complete the charging or discharging process in 1/0.02=50 hours; similarly, 1C=1 hour, 2C=1/2 hour, 3C=1/3 hour, etc.). Furthermore, such S-GO nanocomposite cathode-based Li-S cells exhibit very short cycle life, with the capacity typically decreasing to 60% of its original capacity in less than 40 charge-discharge cycles. decreases below. Due to such short cycle life, this Li-S cell is not useful for practical applications. Another chemical reaction method for depositing S particles on graphene oxide surfaces is disclosed by Wang et al. (US Patent Application Publication No. 2013/0171339; July 4, 2013). This Li-S cell still has the same problem.

A solution precipitation method for preparing graphene-sulfur nanocomposites (with sulfur particles adsorbed on the GO surface) for use as cathode material in Li-S cells has been disclosed by Liu et al. (U.S. Pat. Application Publication No. 2012/0088154; April 12, 2012). The method involves mixing GO sheets and S in a solvent (CS ₂ ) to form a suspension. The solvent is then evaporated to yield a solid nanocomposite, which is then ground to yield a nanocomposite powder having primary sulfur particles with an average diameter of less than about 50 nm. Unfortunately, this method does not seem to be able to produce S particles smaller than 40 nm. The resulting Li-S cell has a very short cycle life (50% capacity decay after only 50 cycles). Even when these nanocomposite particles are encapsulated in polymers, the Li-S cell retains less than 80% of its original capacity after 100 cycles. This cell also exhibits poor rate performance (specific capacity of 1,050 mAh/g (S weight) at a rate of 0.1 C, dropping to <580 mAh/g at a rate of 1.0 C). Again, this suggests that a high proportion of S does not contribute to lithium storage, resulting in low S utilization efficiency.

Additionally, all of the aforementioned methods involve depositing S particles onto the surface of isolated graphene sheets. The presence of S particles (one of the most insulating materials) attached to the graphene surface makes the resulting electrode structure non-conductive when multiple S-bonded graphene sheets are packed together. These S particles prevent the graphene sheets from touching each other and otherwise make it impossible to conduct the graphene sheets to form a 3-D network of electronic conduction paths at the cathode. This unintended and unexpected result is another reason why the performance of these prior art Li-S cells is so low.

Various approaches have been proposed for the fabrication of high energy density Li-S cells, including cathode materials, fabrication processes, There remains a need for and methods of cell operation that improve the utilization efficiency of electroactive cathode materials (S utilization efficiency) and provide rechargeable Li-S cells with high capacity over multiple cycles.

Most importantly, lithium metal (including pure lithium, lithium alloys with high lithium content with other metal elements, or lithium-containing compounds with high lithium content; e.g. >80% by weight or more, or preferably >90 wt% Li) still provides the highest anode specific capacity compared to virtually all other anode active materials (except pure silicon, however silicon has powdering problems) do. If dendrite-related issues could be addressed, lithium metal would be an ideal anode material in lithium-sulfur secondary batteries.

Sodium metal (Na) and potassium metal (K) have similar chemical properties as Li and are used as sulfur cathodes in room temperature sodium-sulfur cells (RT Na-S cells) or potassium-sulfur cells (K-S). face the same problems observed in Li-S cells, such as (i) low active material utilization, (ii) low cycle life, and (iii) low Coulombic efficiency. Again, these drawbacks are mainly caused by the insulating nature of S, the dissolution of S and polysulfide Na or K intermediates in the liquid electrolyte (and associated shuttle effects), and large volume changes during charging and discharging.

It is therefore an object of the present invention to provide rechargeable alkali metal cells (eg, Li-S, Na-S, and KS cells) that exhibit exceptionally high specific energy or high energy density. One particular technical goal of the present invention is to provide an alkali metal with a cell specific energy (all based on the total weight of the cell) of greater than 400 Wh/kg, preferably greater than 500 Wh/kg, more preferably greater than 600 Wh/kg. - Sulfur or alkali ions - To provide a sulfur cell.

Another object of the present invention is to provide a high cathode specific capacity (greater than 1,200 mAh/g based on the weight of sulfur, or a combination of weights of sulfur, conductive additive or substrate, and binder); It is an object of the present invention to provide an alkali metal-sulfur cell exhibiting an alkali metal-sulfur cell exhibiting an energy efficiency of greater than 1,000 mAh/g (based on the cathode composite weight, excluding the weight of the cathode current collector). Preferably, the specific capacity is greater than 1,400 mAh/g based on sulfur weight alone, or greater than 1,200 mAh/g based on cathode composite weight. This must be accompanied by high specific energy, good resistance to dendrite formation, and long and stable cycle life.

In most of the published literature reports (scientific papers) and patent literature, scientists or inventors estimate the cathode specific capacity based solely on the weight of sulfur or lithium polysulfide (rather than the total weight of the cathode composite). Unfortunately, these Li-S cells typically contain a high proportion of inactive materials (materials that cannot store lithium, such as conductive additives and binders). Note that it is used. For practical purposes, it is more meaningful to use capacitance values based on the weight of the cathode composite.

It is therefore a particular object of the present invention to develop a rechargeable alkali metal-sulfur cell based on rational materials and cell design that overcomes or significantly reduces the following problems commonly associated with conventional Li-S cells: (a) dendrite formation (internal short circuit); (b) very low electrical and ionic conductivity of sulfur. This requires a large proportion (typically 30-55%) of non-active conductive fillers and has a significant proportion of inaccessible or inaccessible sulfur or alkali metal polysulfides; c) dissolution of the S and alkali metal polysulfides into the electrolyte, and (d) migration of the polysulfides from the cathode to the anode, where they irreversibly react with lithium or Na or K. This results in loss of active material and capacity decay (shuttle effect); and (e) short cycle life.

The present invention provides alkali metal-sulfur cells (eg, lithium-sulfur cells, sodium-sulfur cells, and potassium-sulfur cells). The alkali metal-sulfur cell comprises (a) an anode active material layer and an optional anode current collector supporting the anode active material layer; and (b) a cathode active material layer and an optional cathode supporting the cathode active material layer. (c) an electrolyte having an optional porous separator layer in ion contact with the anode active material layer and the cathode active material layer, where the cathode active material layer comprises a sulfur-carbon hybrid; a plurality of microparticles of a sulfur-containing material selected from a sulfur-graphite hybrid, a sulfur-graphene hybrid, a conductive polymer-sulfur hybrid, a metal sulfide, a sulfur compound, or a combination thereof, at least one of the microparticles containing an additive; or recoverable tensile strain of 10% or more when measured without reinforcement, lithium ion conductivity of 10 ^-5 S/cm or more (typically 10 ^-5 S/cm to 5 measured at room temperature) ×10 ⁻² S/cm) and a thickness of 0.5 nm to 10 μm (typically 1 nm to 1 μm, but preferably <100 nm, more preferably <10 nm). Consisting of one or more sulfur-containing material particles that are wrapped or encapsulated.

Sulfur-carbon hybrids, sulfur-graphite hybrids, sulfur-graphene hybrids, or conductive polymer-sulfur hybrids are mixtures, blends, composites, or combinations of sulfur or sulfides with carbon, graphite, graphene, or conductive polymer materials. It can be a chemically or physically bound object. For example, a sulfur-graphene hybrid can be a simple mixture of sulfur and graphene (in particle form) prepared by ball milling. Such hybrids may include sulfur bound at a surface such as a graphene oxide sheet. As another example, the sulfur-carbon hybrid can be a simple mixture of sulfur and carbon nanotubes (in particle form), or can include sulfur present in the pores of activated carbon particles.

In the rechargeable alkali metal-sulfur cell of the present invention, the highly elastic polymer has ether bonds, nitrile-derived bonds, benzoyl peroxide-derived bonds, ethylene oxide bonds, propylene oxide bonds, vinyl alcohol bonds, cyano- It may include the aforementioned crosslinked networks of polymer chains having resin bonds, triacrylate monomer-derived bonds, tetraacrylate monomer-derived bonds, or combinations thereof.

In some preferred embodiments, the high modulus polymer includes nitrile-containing polyvinyl alcohol chains, cyano resin chains, pentaerythritol tetraacrylate chains, pentaerythritol triacrylate chains, ethoxylated trimethylolpropane triacrylate (ETPTA) chains, ethylene glycol methyl It comprises a cross-linked network of polymer chains selected from ether acrylate (EGMEA) chains, or combinations thereof.

In a rechargeable alkali metal-sulfur cell, the metal sulfide may include a material represented by M _x S _y , where x is an integer from 1 to 3 and y is an integer from 1 to 10; M is a metal element selected from an alkali metal, an alkali metal selected from Mg or Ca, a transition metal, a metal from Groups 13 to 17 of the periodic table, or a combination thereof. Preferably, the metal element M is selected from Li, Na, K, Mg, Zn, Cu, Ti, Ni, Co, Fe, or Al.

In some preferred embodiments, the metal sulfide _of the cathode layer is _Li2S1 , _{Li2S2 , Li2S3 , Li2S4 , Li2S5 , Li2S6 , Li2S7 , Li2S8 , Li2S9 , Li2S10 , Na2S1 , Na2S2 , Na2S3 , Na2S4 , Na2S5 , Na2S6 , Na2S7 , Na2S8 , Na2S9 , Na2S10 , K2S1 , K2S2 , K2S3 , K2S4 , K2S5 , K2S6 , K2S7 ,} Contains K ₂ S ₈ , K ₂ S ₉ , or K ₂ S ₁₀ .

In rechargeable alkali metal-sulfur cells, the carbon or graphite material of the cathode active material layer can be mesophase pitch, mesophase carbon, mesocarbon microbeads (MCMB), coke particles, expanded graphite flakes, artificial graphite particles, natural graphite particles, high Can be selected from oriented pyrolytic graphite, soft carbon particles, hard carbon particles, carbon nanotubes, carbon nanofibers, carbon fibers, graphite nanofibers, graphite fibers, carbonized polymer fibers, activated carbon, carbon black, or combinations thereof. . Graphene can be selected from pure graphene, graphene oxide, reduced graphene oxide (RGO), fluorinated graphene, nitrogenated graphene, hydrogenated graphene, doped graphene, functionalized graphene, or combinations thereof.

The conductive polymer-sulfur hybrid may preferably comprise an inherently conductive polymer selected from polyaniline, polypyrrole, polythiophene, polyfuran, bicyclic polymers, sulfonated derivatives thereof, or combinations thereof.

In certain embodiments, the high modulus polymer comprises from 0.1% to 50% by weight of a lithium ion conductive additive dispersed therein, or carbon nanotubes, carbon nanofibers, graphene, or combinations thereof. 0.1% to 10% by weight of reinforcing nanofilaments selected from.

In certain embodiments, a high modulus polymer is mixed with a lithium ion conductive additive to form a composite, wherein said lithium ion conductive additive is dispersed in said high modulus polymer; Li ₂ CO ₃ , Li ₂ O, Li ₂ C ₂ O ₄ , LiOH, LiX, ROCO ₂ Li, HCOLi, ROLi, (ROCO ₂ Li) ₂ , (CH ₂ OCO ₂ Li) ₂ , Li ₂ S, Li _x SO _y , or a combination thereof, where X=F, Cl, I, or Br, R=hydrocarbon group, x=0-1, y=1-4.

In certain embodiments, a high modulus polymer is mixed with a lithium ion conductive additive to form a composite, where the lithium ion conductive additive is dispersed in the high modulus polymer and lithium perchlorate. , LiClO ₄ , lithium hexafluorophosphate, LiPF ₆ , lithium borofluoride, LiBF ₄ , lithium hexafluoroarsenide, LiAsF ₆ , lithium trifluoromethanesulfonate, LiCF ₃ SO ₃ , lithium bis-trifluoromethylsulfonylimide, LiN(CF ₃ SO ₂ ) ₂ , lithium bis(oxalato)borate, LiBOB, lithium oxalyl difluoroborate, LiBF ₂ C ₂ O ₄ , lithium oxalyl difluoroborate, LiBF ₂ C ₂ O ₄ , lithium nitrate, LiNO ₃ , Li- Fluoroalkyl-phosphoric acid, LiPF ₃ (CF ₂ CF ₃ ) ₃ , lithium bisberfluoro-ethylsulfonylimide, LiBETI, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonylimide, selected from LiTFSI, ionic liquid-based lithium salts, or combinations thereof.

In certain preferred embodiments, the high modulus polymer is mixed with a conductive polymer selected from polyaniline, polypyrrole, polythiophene, polyfuran, bicyclic polymers, sulfonated derivatives thereof, or combinations thereof.

In certain embodiments, the high modulus polymers include poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVdF). ), polybis-methoxyethoxyethoxide-phosphazenex, polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), sulfonated derivatives thereof, or combinations thereof. form a mixture or blend with a lithium ion conductive polymer.

Typically, high modulus polymers have a lithium ion conductivity of 1×10 ⁻⁵ S/cm to 5×10 ⁻² S/cm at room temperature.

Rechargeable alkali metal-sulfur cells have sulfur utilization efficiencies of 80% to 99%, more typically 85% to 97%.

In rechargeable alkali metal-sulfur cells, the electrolyte is selected from polymer electrolytes, polymer gel electrolytes, composite electrolytes, ionic liquid electrolytes, non-aqueous liquid electrolytes, soft matter phase electrolytes, solid electrolytes, or combinations thereof. The electrolytes include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and lithium trifluorometasulfonate (LiCF _{3SO3 )} , lithium bis-trifluoromethylsulfonylimide ₍ LiN( _{CF3SO2 ) 2)} , lithium bis ₍ oxalato)borate (LiBOB), lithium oxalyldifluoroborate ( _LiBF2C2O4 ), oxalyldifluoro Lithium borate (LiBF ₂ C ₂ O ₄ ), Lithium nitrate (LiNO ₃ ), Li-fluoroalkyl-phosphate (LiPF ₃ (CF ₂ CF ₃ ) ₃ ), Lithium bisperfluoroethylsulfonylimide (LiBETI), Ion Liquid salts, sodium perchlorate (NaClO ₄ ), potassium perchlorate (KClO ₄ ), sodium hexafluorophosphate (NaPF ₆ ), potassium hexafluorophosphate (KPF ₆ ), sodium borofluoride (NaBF ₄ ), Potassium borofluoride (KBF ₄ ), sodium hexafluoromethane arsenide, potassium hexafluoroarsenide, sodium trifluoromethanesulfonate (NaCF ₃ SO ₃ ), potassium trifluoromethanesulfonate (KCF ₃ SO ₃ ), bis-trifluoromethane Selected from sodium fluoromethylsulfonylimide (NaN(CF ₃ SO ₂ ) ₂ ), sodium trifluoromethanesulfonimide (NaTFSI), potassium bis-trifluoromethylsulfonylimide (KN(CF ₃ SO ₂ ) ₂ ), or combinations thereof It may also contain salts.

Solvents include ethylene carbonate (EC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), ethyl propionate, methyl propionate, propylene carbonate (PC), and γ-butyrolactone (γ-BL). , acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, xylene or methyl acetate (MA), fluoroethylene carbonate (FEC), vinylene carbonate (VC), allylethyl carbonate ( AEC), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DEGDBE), 2-ethoxy It can be selected from ethyl ether (EEE), sulfone, sulfolane, room temperature ionic liquid, or combinations thereof.

In certain embodiments, the anode active material layer comprises lithium metal, sodium metal, potassium metal, lithium metal alloy, sodium metal alloy, potassium metal alloy, lithium intercalation compound, sodium intercalation compound, potassium intercalation compound , lithiated compounds, sodated compounds, potassium-doped compounds, lithiated titanium dioxide, lithium titanate, lithium manganate, lithium transition metal oxides, Li ₄ Ti ₅ O ₁₂ , or combinations thereof. Contains substances.

The rechargeable alkali metal-sulfur cell may be a lithium ion-sulfur cell, in which case the anode active material layer comprises (a) silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), titanium (Ti), iron (Fe), and Cadmium (Cd) and lithiated versions thereof; (b) alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, or Cd with other elements; and lithiated versions thereof; version, in which case said alloy or compound is stoichiometric or non-stoichiometric, (c) Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ni, Co, oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides of Ti, Mn, or Cd, and mixtures or composites thereof, and lithiated versions thereof; (d) salts of Sn; hydroxides and lithiated versions thereof; (e) carbon or graphite materials and prelithiated versions thereof; and combinations thereof.

The rechargeable alkali metal-sulfur cell may be a sodium ion-sulfur cell or a potassium ion-sulfur cell, in which case the anode active material layer comprises (a) sodium or potassium doped silicon ( Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), titanium (Ti), cobalt (Co), nickel ( Ni), manganese (Mn), cadmium (Cd), and mixtures thereof; (b) Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof; mixtures of sodium- or potassium-containing alloys or intermetallic compounds, (c) Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or complexes thereof; (d) Sodium or potassium salts, (e) Graphite particles, hard carbon, soft The anode active material is selected from the group consisting of carbon or carbon particles, and presodiumated versions thereof, and combinations thereof.

Preferably, in a rechargeable alkali metal-sulfur cell, the particulates contain from 80% to 99% by weight of sulfur, metal sulfide, or metal compound, based on the combined weight of the high capacity polymer and the sulfur, metal sulfide, or metal compound. Contains metal compounds.

The present invention also provides a cathode active material layer in a rechargeable alkali metal-sulfur cell. The cathode active material layer includes a plurality of fine particles of a sulfur-containing material selected from sulfur-carbon hybrids, sulfur-graphite hybrids, sulfur-graphene hybrids, conductive polymer-sulfur hybrids, metal sulfides, sulfur compounds, or combinations thereof. and at least one of the particulates has a recoverable tensile strain of 10% or more when measured without additives or reinforcements, a lithium ion conductivity of 10 ⁻⁵ S/cm or more at room temperature (typically (up to 5×10 ⁻² S/cm), and wrapped by a thin layer of highly elastic polymer having a thickness of 0.5 nm to 10 μm (preferably typically 1 nm to 1 μm, more preferably <100 nm). one or more sulfur-containing material particles that are encapsulated or encapsulated.

In this product (cathode layer), a sulfur-carbon hybrid, sulfur-graphite hybrid, sulfur-graphene hybrid, or conductive polymer-sulfur hybrid combines sulfur or sulfide with carbon, graphite, graphene, or conductive polymer material. A mixture, blend, complex, chemical or physical combination of

In this cathode active material layer product, the highly elastic polymer preferably contains ether bonds, nitrile-derived bonds, benzoyl peroxide-derived bonds, ethylene oxide bonds, propylene oxide bonds, vinyl alcohol bonds, cyano- It includes a crosslinked network of polymer chains having resin bonds, bonds derived from triacrylate monomers, bonds derived from tetraacrylate monomers, or combinations thereof. Preferably, the high modulus polymer is a nitrile-containing polyvinyl alcohol chain, a cyano resin chain, a pentaerythritol tetraacrylate chain, a pentaerythritol triacrylate chain, an ethoxylated trimethylolpropane triacrylate (ETPTA) chain, an ethylene glycol methyl ether acrylate (EGMEA) chain. chains, or a cross-linked network of polymer chains selected from combinations thereof.

In the cathode active material layer, the metal sulfide may include M _x S _y , where x is an integer from 1 to 3, y is an integer from 1 to 10, and M is an alkali metal, Mg or Ca A metal element selected from alkali metals selected from, transition metals, metals from groups 13 to 17 of the periodic table, or a combination thereof.

The carbon or graphite material of the cathode active material layer includes mesophase pitch, mesophase carbon, mesocarbon microbeads (MCMB), coke particles, expanded graphite flakes, artificial graphite particles, natural graphite particles, highly oriented pyrolytic graphite, soft carbon particles, It can be selected from hard carbon particles, carbon nanotubes, carbon nanofibers, carbon fibers, graphite nanofibers, graphite fibers, carbonized polymer fibers, activated carbon, carbon black, or combinations thereof.

The cathode active material layer further includes a binder resin that binds the plurality of particulates (encapsulated sulfur-containing particles) together to form the cathode active material layer, in which case the binder resin binds the plurality of particulates together. It is not part of (i.e., not included inside the core portion of the microparticles) but is external to the plurality of microparticles. In other words, the high modulus polymer does not wrap around the binder resin.

Alternatively, the present invention provides a cathode active material layer in a rechargeable alkali metal-sulfur cell, where the cathode active material layer comprises a resin binder, an optional conductive additive, and a sulfur-carbon hybrid; a plurality of particles of a sulfur-containing material selected from a sulfur-graphite hybrid, a sulfur-graphene hybrid, a conductive polymer-sulfur hybrid, a metal sulfide, a sulfur compound, or a combination thereof, the sulfur-containing material particles bound by a resin binder; to form an integrated solid layer (a layer of adequate structural integrity that is capable of self-supporting), the integrated solid layer has a recoverable tensile strain of 10% or more when measured without additives or reinforcements, It is covered and protected by a thin layer of highly elastic polymer with a lithium ion conductivity of more than 10 ⁻⁵ S/cm at room temperature and a thickness of 0.5 nm to 10 μm. In some embodiments, the integrated solid layer is bonded to the cathode current collector by a resin binder.

Such a high modulus polymeric protective layer is created by spraying a mass of precursor (monomer or oligomer with the necessary initiator or curing agent) onto a prefabricated cathode active material layer, which is then polymerized and crosslinked. Can be formed.

The present invention also provides a rechargeable alkali metal-sulfur cell comprising such a cathode active material layer protected by a high modulus polymer. The alkali metal-sulfur cell includes (a) an anode active material layer and an optional anode current collector supporting the anode active material layer; (b) a cathode including the cathode active material layer; and (c) an anode active material layer. an electrolyte with an optional porous separator layer in ionic contact with the material layer and the cathode active material layer.

The present invention also provides powder agglomerate products for use in lithium-sulfur battery cathodes. the powder mass comprises a plurality of microparticles of a sulfur-containing material selected from sulfur-carbon hybrids, sulfur-graphite hybrids, sulfur-graphene hybrids, conductive polymer-sulfur hybrids, metal sulfides, sulfur compounds, or combinations thereof; At least one of the aforementioned microparticles has a recoverable tensile strain of 10% or more when measured without additives or reinforcements, a lithium ion conductivity of 10 ⁻⁵ S/cm or more at room temperature, and a lithium ion conductivity of 0.5 nm to 0.5 nm. It consists of one or more sulfur-containing material particles wrapped or encapsulated by a thin layer of highly elastic polymer having a thickness of 10 μm.

In the powder mass, the sulfur-carbon hybrid, sulfur-graphite hybrid, sulfur-graphene hybrid, or conductive polymer-sulfur hybrid is a mixture, blend, composite, or combination of sulfur or sulfide with carbon, graphite, graphene, or conductive polymer. It is an object that is chemically or physically bonded to a polymeric material. Highly elastic polymers have ether bonds, nitrile-derived bonds, benzoyl peroxide-derived bonds, ethylene oxide bonds, propylene oxide bonds, vinyl alcohol bonds, cyano-resin bonds, triacrylate monomer-derived bonds, and tetraacrylate monomer bonds in the crosslinked network of the polymer chain. or a combination of these. Preferably, the high modulus polymer is a nitrile-containing polyvinyl alcohol chain, a cyano resin chain, a pentaerythritol tetraacrylate chain, a pentaerythritol triacrylate chain, an ethoxylated trimethylolpropane triacrylate (ETPTA) chain, an ethylene glycol methyl ether acrylate (EGMEA) chain. chains, or a cross-linked network of polymer chains selected from combinations thereof.

In the powder mass, the metal sulfide may include M _x S _y , where x is an integer from 1 to 3, y is an integer from 1 to 10, and M is selected from an alkali metal, Mg or Ca. metal elements selected from alkali metals, transition metals, metals from groups 13 to 17 of the periodic table, or combinations thereof.

The present invention also provides a method of manufacturing a rechargeable alkali metal-sulfur cell. The method includes (a) providing a cathode and an optional cathode current collector supporting the cathode; and (b) an alkali metal anode selected from Li, Na, K, or combinations thereof and supporting the anode. (c) providing an electrolyte in contact with the anode and cathode and an optional separator electrically separating the anode and cathode, wherein: The cathode includes a plurality of microparticles of a sulfur-containing material, at least one of the microparticles having a recoverable tensile strain of 10% to 700% (more typically 30%) when measured without additives or reinforcements. 300%), lithium ion conductivity of 10 ⁻⁵ S/cm or higher at room temperature (typically 1×10 ⁻⁵ S/cm to 5×10 ⁻² S/cm), and 0.5 nm to 10 μm ( It consists of one or more sulfur-containing material particles wrapped or encapsulated by a thin layer of highly elastic polymer having a thickness of preferably 1 nm to 1 μm, more preferably 1 nm to 100 nm, most preferably 1 nm to 10 nm).

In the above manufacturing method, the sulfur-containing material is preferably selected from sulfur-carbon hybrids, sulfur-graphite hybrids, sulfur-graphene hybrids, conductive polymer-sulfur hybrids, metal sulfides, sulfur compounds, or combinations thereof. A sulfur-carbon hybrid, sulfur-graphite hybrid, sulfur-graphene hybrid, or conductive polymer-sulfur hybrid is a mixture, blend, composite, or combination of sulfur or sulfide and carbon, graphite, graphene, or conductive polymer material. It is an object that is chemically or physically bound together.

In the production method of the present invention, the highly elastic polymer has ether bonds, nitrile-derived bonds, benzoyl peroxide-derived bonds, ethylene oxide bonds, propylene oxide bonds, vinyl alcohol bonds, cyano-resin bonds, and triacrylate bonds in the crosslinked network of polymer chains. including the aforementioned crosslinked networks of polymer chains having monomer-derived linkages, tetraacrylate monomer-derived linkages, or combinations thereof. Preferably, the high modulus polymer is a nitrile-containing polyvinyl alcohol chain, a cyano resin chain, a pentaerythritol tetraacrylate chain, a pentaerythritol triacrylate chain, an ethoxylated trimethylolpropane triacrylate (ETPTA) chain, an ethylene glycol methyl ether acrylate (EGMEA) chain. chains, or a cross-linked network of polymer chains selected from combinations thereof.

In the manufacturing method, the operations providing a plurality of microparticles include pan coating, air suspension, centrifugal extrusion, vibrating nozzle, spray drying, ultrasonic atomization, coacervation phase separation, interfacial polycondensation, in situ polymerization, matrix polymerization, or It may include encapsulating or wrapping one or more sulfur-containing material particles with the aforementioned thin layer of high modulus polymer using a procedure selected from a combination of these.

In some embodiments, the operation of providing a plurality of microparticles comprises one or more of the foregoing in a mixture of the foregoing high modulus polymers with elastomers, conductive polymers, lithium ion conductive materials, reinforcements, or combinations thereof. encapsulating or wrapping the sulfur-containing material particles. Preferably, the lithium ion conductive material is dispersed in the above-mentioned high modulus polymers, such as Li ₂ CO ₃ , Li ₂ O, Li ₂ C ₂ O ₄ , LiOH, LiX, ROCO ₂ Li, HCOLi, ROLi, (ROCO ₂ Li) ₂ , (CH ₂ OCO ₂ Li) ₂ , Li ₂ S, Li _x SO _y , or a combination thereof, where X=F, Cl, I, or Br, R=hydrocarbon group , x=0-1, y=1-4.

In certain embodiments, the lithium ion conductive material is dispersed in the high modulus polymers described above, including lithium perchlorate, LiClO ₄ , lithium hexafluorophosphate, LiPF ₆ , lithium borofluoride, LiBF ₄ , hexafluorocarbon, etc. Lithium oxide, LiAsF ₆ , lithium trifluoromethanesulfonate, LiCF ₃ SO ₃ , lithium bis-trifluoromethylsulfonylimide, LiN(CF ₃ SO ₂ ) ₂ , lithium bis(oxalato)borate, LiBOB, lithium oxalyl difluoroborate, LiBF ₂ C ₂ O ₄ , Lithium oxalyl difluoroborate, LiBF ₂ C ₂ O ₄ , Lithium nitrate, LiNO ₃ , Li-fluoroalkyl-phosphoric acid, LiPF ₃ (CF ₂ CF ₃ ) ₃ , Lithium bisberfluoro-ethylsulfonylimide , LiBETI, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonimide, LiTFSI, ionic liquid-based lithium salts, or combinations thereof.

In the present Li-S cells, the reversible specific capacity of the sulfur cathode is typically and preferably greater than 1000 mAh per gram, and often exceeds 1200 mAh or even 1500 mAh per gram of the entire cathode layer. The high specific capacity of the cathode of the present invention, when combined with a lithium anode, typically significantly exceeds 400 Wh/kg, based on the combined total cell weight including anode, cathode, electrolyte, separator, and current collector. yielding a cell specific energy exceeding This particular energy value is not based solely on the weight of the cathode active material or the weight of the cathode layer (as was sometimes done in published literature or patent applications); instead, it is based on the entire weight of the cell. . In many cases, the cell specific energy is higher than 500 Wh/kg, and in some cases exceeds 600 Wh/kg.

The present invention also provides another method of manufacturing a rechargeable alkali metal-sulfur cell selected from a lithium-sulfur cell, a sodium-sulfur cell, or a potassium-sulfur cell. The method includes the steps of: (a) providing an anode including an anode active material layer and an optional anode current collector supporting the anode active material layer; and (b) a cathode active material protected and covered with a high modulus polymer. (c) providing an electrolyte with an optional porous separator layer in ion contact with the anode active material layer and the cathode active material layer; and (d) the anode, the cathode, and the electrolyte. forming a battery unit, and placing the battery unit in a protective housing to form a rechargeable alkali metal-sulfur cell.

Also provided is a method of manufacturing a rechargeable alkali metal-sulfur cell selected from a lithium-sulfur cell, a sodium-sulfur cell, or a potassium-sulfur cell. The method includes the steps of: (a) providing an anode comprising an anode active material layer and an optional anode current collector supporting the anode active material layer; and (b) optionally a cathode supported by the cathode current collector. (c) providing a porous separator layer and an electrolyte in ion contact with the anode active material layer and the cathode active material layer; (d) providing a cathode active material layer and a separator; and implementing a layer of high modulus polymer in between. This highly modulus polymer has a recoverable tensile strain of greater than 10% when measured without additives or reinforcements, a lithium ion conductivity of greater than 10 ⁻⁵ S/cm at room temperature, and a thickness of 0.5 nm to 10 μm. It has a certain quality. This layer serves to prevent the diffusion of sulfur or metal polysulfides (eg lithium polysulfide or sodium polysulfide) dissolved in the cathode from migrating to the anode side. This effectively reduces or eliminates the shuttle effect.

These and other advantages and features of the invention will become more apparent from the following description of the best mode implementation and illustrative examples.

FIG. 1(A) is a schematic diagram of a prior art alkali metal-sulfur battery cell. FIG. 1(B) is a schematic diagram of another prior art alkali metal-sulfur battery cell. Figure 2 illustrates the problems associated with the cathode active materials of prior art alkali metal batteries, such as metal sulfide particles encapsulated in a protective shell (e.g., carbon shell) in a core-shell structure, which inevitably leads to shell failure. The metal sulfide particles encapsulated in the protective layer lead to poor contact between the contracted metal sulfide particles and the rigid protective shell during battery charging. FIG. 3 is a schematic representation of particles encapsulated with a high modulus polymer of the present invention of a cathode active material. The high elastic deformation of the polymer shell allows the shell to expand and contract in conformity with the core particle. FIG. 4 is a schematic diagram of S-containing cathode active material particles wrapped in four types of high modulus polymers. Figure 5 is a representative tensile stress-strain curve for ETPTA polymer initiated and crosslinked with four BPOs. Figure 6 is a representative tensile stress-strain curve for four PF5 initiated and crosslinked PVA-CN polymers. Figure 7 is a representative tensile stress-strain curve for three cross-linked PETEA polymers. Figure 8 shows S/CNTs with (1) ETPTA polymer encapsulated S/CNT particles, (2) carbon encapsulated C/CNT particles, and (3) unprotected S/CNT particles, respectively. Specific capacity values of three Li-S cells with cathode active materials. Figure 9 shows the identification of two Li-S cells each having a cathode active material layer comprising (1) high modulus polymer encapsulated S/graphene hybrid particles and (2) unprotected S/graphene hybrid particles, respectively. value. FIG. 10 shows a cathode active material layer comprising (1) sulfur-MCMB (activated) composite particles encapsulated with highly elastic cross-linked ETPTA polymer, and (2) unprotected sulfur-MCMB (activated) composite particles, respectively. Specific values of two Na-S cells with . Figure 11 shows the Ragone plot (cell power density versus cell energy density) of two Li metal-sulfur cells: one has a cathode layer consisting of highly elastic polymer-encapsulated particles of S-coated graphene sheets; and the other comprises a cathode layer of unencapsulated particles. Figure 12 shows the Ragone plot (cell energy density vs. cell energy density) of four alkali metal-sulfur cells: highly elastic polymer-encapsulated particles of exfoliated graphite worms electrochemically impregnated with sulfur. Na-S cell with non-encapsulated particles of exfoliated graphite worms electrochemically impregnated with sulfur, high elastic polymer of exfoliated graphite worms electrochemically impregnated with sulfur KS cells with particles encapsulated in S and KS cells with unprotected S-impregnated graphite worms.

For convenience, the following discussion of preferred embodiments is primarily based on Li-S cells, but the same or similar compounds, structures and methods are applicable to Na-S and KS cells. Examples of a Li-S cell, a room temperature Na-S cell, and a KS cell are shown.

A. Alkali metal-sulfur cell (use lithium-sulfur cell as an example)
The specific capacity and specific energy of a Li-S cell (or Na-S, or K-S cell) are determined by the actual amount of sulfur that can be implemented in the cathode active layer (compared to other non-active components, binder resin and conductive fillers), as well as the utilization efficiency of this amount of sulfur (ie, the utilization efficiency of the cathode active material or the actual proportion of S actively participating in the storage and release of lithium ions). Using Li-S cells as an illustrative example, high-capacity and high-energy Li-S cells contain a large amount of S (i.e., binder resins, conductive additives, and other modifications or supports) in the cathode active layer. (relative to the amount of non-active materials such as carbon dioxide) as well as high S utilization efficiency. The present invention provides such cathode active layers, their constituent powder mass products, the resulting Li-S cells, and methods of making such cathode active layers and cells.

The alkali metal-sulfur cell comprises (a) an anode active material layer and an optional anode current collector supporting the anode active material layer; and (b) a cathode active material layer and an optional cathode supporting the cathode active material layer. (c) an electrolyte having an optional porous separator layer in ion contact with the anode active material layer and the cathode active material layer, where the cathode active material layer comprises a sulfur-carbon hybrid; a plurality of microparticles of a sulfur-containing material selected from a sulfur-graphite hybrid, a sulfur-graphene hybrid, a conductive polymer-sulfur hybrid, a metal sulfide, a sulfur compound, or a combination thereof, at least one of the particles being an additive; or recoverable tensile strain of 10% or more when measured without reinforcement, lithium ion conductivity of 10 ^-5 S/cm or more (typically 10 ^-5 S/cm to 5 measured at room temperature) ×10 ⁻² S/cm) and a thickness of 0.5 nm to 10 μm (typically 1 nm to 1 μm, but preferably <100 nm, more preferably <10 nm). Consisting of one or more sulfur-containing material particles that are wrapped or encapsulated.

A sulfur-carbon hybrid, sulfur-graphite hybrid, sulfur-graphene hybrid, or conductive polymer-sulfur hybrid is a mixture, blend, composite, or combination of sulfur or sulfide and carbon, graphite, graphene, or conductive polymer material. may be chemically or physically bound objects. For example, a sulfur-graphene hybrid can be a simple mixture of sulfur and graphene (in particle form) prepared by ball milling. Such hybrids may include sulfur bound to a surface such as a graphene oxide sheet. As another example, the sulfur-carbon hybrid can be a simple mixture of sulfur and carbon nanotubes (in particle form), or can include sulfur present in the pores of activated carbon particles.

In the rechargeable alkali metal-sulfur cell of the present invention, the highly elastic polymer has ether bonds, nitrile-derived bonds, benzoyl peroxide-derived bonds, ethylene oxide bonds, propylene oxide bonds, vinyl alcohol bonds, cyano- It may include the aforementioned crosslinked networks of polymer chains having resin bonds, triacrylate monomer-derived bonds, tetraacrylate monomer-derived bonds, or combinations thereof. In some preferred embodiments, the high modulus polymer preferably comprises nitrile-containing polyvinyl alcohol chains, cyano resin chains, pentaerythritol tetraacrylate chains, pentaerythritol triacrylate chains, ethoxylated trimethylolpropane triacrylate (ETPTA) chains, It comprises a cross-linked network of polymer chains selected from ethylene glycol methyl ether acrylate (EGMEA) chains, or combinations thereof.

In a rechargeable alkali metal-sulfur cell, the metal sulfide may include a material represented by M _x S _y , where x is an integer from 1 to 3, y is an integer from 1 to 10, and M is an alkali metal , Mg or Ca, a transition metal, a metal from groups 13 to 17 of the periodic table, or a combination thereof. Preferably, the metal element M is selected from Li, Na, K, Mg, Zn, Cu, Ti, Ni, Co, Fe, or Al. In some preferred embodiments, the metal sulfide _of the cathode layer is _Li2S1 , _{Li2S2 , Li2S3 , Li2S4 , Li2S5 , Li2S6 , Li2S7 , Li2S8 , Li2S9 , Li2S10 , Na2S1 , Na2S2 , Na2S3 , Na2S4 , Na2S5 , Na2S6 , Na2S7 , Na2S8 , Na2S9 , Na2S10 , K2S1 , K2S2 , K2S3 , K2S4 , K2S5 , K2S6 , K2S7 ,} Contains K ₂ S ₈ , K ₂ S ₉ , or K ₂ S ₁₀ .

In rechargeable alkali metal-sulfur cells, the carbon or graphite material of the cathode active material layer can be mesophase pitch, mesophase carbon, mesocarbon microbeads (MCMB), coke particles, expanded graphite flakes, artificial graphite particles, natural graphite particles, high Can be selected from oriented pyrolytic graphite, soft carbon particles, hard carbon particles, carbon nanotubes, carbon nanofibers, carbon fibers, graphite nanofibers, graphite fibers, carbonized polymer fibers, activated carbon, carbon black, or combinations thereof. . Graphene can be selected from pure graphene, graphene oxide, reduced graphene oxide (RGO), fluorinated graphene, nitrogenated graphene, hydrogenated graphene, doped graphene, functionalized graphene, or combinations thereof.

The conductive polymer-sulfur hybrid may preferably comprise an inherently conductive polymer selected from polyaniline, polypyrrole, polythiophene, polyfuran, bicyclic polymers, sulfonated derivatives thereof, or combinations thereof. This can be a simple mixture of sulfur or metal sulfide and a conductive polymer.

In certain embodiments, the high modulus polymer comprises from 0.1% to 50% by weight of a lithium ion conductive additive dispersed therein, or carbon nanotubes, carbon nanofibers, graphene, or combinations thereof. 0.1% to 10% by weight of reinforcing nanofilaments selected from. The lithium ion conductive additive forms a composite, in which the aforementioned lithium ion conductive additive is dispersed in the aforementioned high modulus polymer and contains Li ₂ CO ₃ , Li ₂ O, Li ₂ C ₂ O ₄ , LiOH, LiX, _ROCO2Li , HCOLi, ROLi, ( _ROCO2Li ) _{2 , (} CH2OCO2Li) ₂ , _Li2S , _LixSOy , or a combination _thereof , in which case , X=F, Cl, I, or Br, R=hydrocarbon group, x=0-1, y=1-4.

Lithium ion conductive additives can be dispersed in high modulus polymers, such as lithium perchlorate, _LiClO4 , lithium hexafluorophosphate, _LiPF6 , lithium borofluoride, _LiBF4 , lithium hexafluorarsenide, _LiAsF6 , Lithium trifluoromethanesulfonate, LiCF ₃ SO ₃ , lithium bis-trifluoromethylsulfonylimide, LiN(CF ₃ SO ₂ ) ₂ , lithium bis(oxalato)borate, LiBOB, lithium oxalyl difluoroborate, LiBF ₂ C ₂ O ₄ , Lithium oxalyl difluoroborate, LiBF ₂ C ₂ O ₄ , Lithium nitrate, LiNO ₃ , Li-fluoroalkyl-phosphoric acid, LiPF ₃ (CF ₂ CF ₃ ) ₃ , Lithium bisberfluoro-ethylsulfonylimide, LiBETI, Lithium bis( It can be selected from trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonimide, LiTFSI, ionic liquid-based lithium salts, or combinations thereof.

Highly modulus polymer refers to a polymer, typically a lightly crosslinked polymer, that exhibits an elastic deformation of at least 10% when measured in uniaxial tension (no additives or reinforcements in the polymer). In the field of materials science and engineering, "elastic deformation" is defined as a deformation of a material (when subjected to mechanical stress) that is fully recoverable in nature and where recovery is essentially instantaneous upon release of the load. be done. The elastic deformation is preferably greater than 30%, more preferably greater than 50%, even more preferably greater than 100%, even more preferably greater than 150%, and most preferably greater than 200%. Preferred types of high capacity polymers are discussed below.

As shown in FIG. 4, the present invention provides four major types of microparticles of high capacity polymer encapsulated cathode active material particles. The first is a single particle microparticle that includes a cathode active material core 10 (eg, a particle of a sulfur-CNT mixture) encapsulated with a high capacity polymer shell 12. The second includes a plurality of cathode active material particles 14 encapsulated in a high capacity polymer 16, optionally along with other active materials (e.g. particles of graphite or hard carbon, not shown) or conductive additives. (For example, particles of sulfur-graphene mixture, sulfur-carbon black mixture, activated carbon particles having pores impregnated with S, polysulfide lithium particles, etc.). The third is a single particle microparticle comprising a cathode active material core 18 coated with a carbon or graphene layer 20 (or other conductive material) and further encapsulated with a high modulus polymer 22. Fourth, a conductive protective layer 26 (carbon , graphene, etc.). These cathode active material particles can be based on pure sulfur instead of sulfur compounds, metal polysulfides, etc.

As shown schematically at the top of Figure 3, sulfur-based particles can be encapsulated by a bulk polymer shell to form a core-shell structure (in this example a sulfur core and a polymer shell). . When a lithium-sulfur cell is discharged, the cathode active material (eg, the sulfur of S/CNT particles encapsulated in a high capacity polymer) reacts with lithium ions to form polysulfide lithium, which expands in volume. Due to the high elasticity of the encapsulation shell (high capacity polymer), the shell does not split into segments (in contrast to a broken carbon shell). The high capacity polymer shell remains intact, preventing the underlying lithium sulfide from being exposed to the electrolyte, thus preventing it from dissolving into the electrolyte during repeated charging/discharging of the battery. This strategy prevents the continued migration of polysulfide lithium to the anode side where it cannot react with lithium and return to the cathode (shuttle effect). This shuttle effect is primarily responsible for the continuous capacity decay of conventional Li-S, Na-S, or KS cells.

Alternatively, referring to the bottom of FIG. 3, lithium sulfide is used as the cathode active material. A layer of high capacity polymer can be encapsulated around the lithium polysulfide particles to form a core-shell structure. When a Li-S battery is charged and lithium ions are released from the cathode, the cathode active material particles contract. However, high capacity polymers can elastically contract in a conformal manner, so there is no gap between the protective shell and the sulfur. Such configurations are susceptible to subsequent reactions of lithium with sulfur. The high capacity polymer shell expands and contracts with the expansion and contraction of the encapsulated core cathode active material particles, enabling long-term cycle stability of the lithium battery.

B. High Modulus Polymers Preferably and typically, the high capacity polymers have a modulus of at least 10 ⁻⁵ S/cm, more preferably at least 10 ⁻⁴ S/cm, even more preferably at least 10 ⁻³ S/cm, and most preferably at least 10 ^-2 S/cm or higher lithium ion conductivity. In some embodiments, the high capacity polymer is a pure polymer with no additives or fillers dispersed therein. In other embodiments, the high capacity polymer comprises a polymer matrix comprising 0.1% to 50% (preferably 1% to 35%) by weight of a lithium ion conductive additive dispersed in the high capacity polymeric matrix material. It is a complex. High capacity polymers need to have high elasticity (elastic deformation strain value >10%). Elastic deformation is a fully recoverable deformation, and the recovery process is essentially instantaneous (no significant time delay). High capacity polymers range from 10% to 1,000% (10 times original length), more typically 10% to 800%, even more typically 50% to 500%, most typically and desirably exhibit an elastic deformation of 70% to 300%. Typically, metals have high ductility (i.e., can be expanded significantly without breaking), but the majority of the deformation is plastic (non-recoverable), with only a small amount of elastic deformation (typically <1%, more typically <0.2%).

In some preferred embodiments, the high modulus polymer has ether linkages, nitrile-derived linkages, benzoyl peroxide-derived linkages, ethylene oxide linkages, propylene oxide linkages, vinyl alcohol linkages, cyano-resin linkages, tri- Includes lightly cross-linked network polymer chains having linkages derived from acrylate monomers, tetraacrylate monomer-derived linkages, or combinations thereof. These networks or crosslinked polymers exhibit a unique combination of high elasticity (high elastic deformation strain) and high lithium ion conductivity.

In certain preferred embodiments, the high modulus polymers include nitrile-containing polyvinyl alcohol chains, cyano resin chains, pentaerythritol tetraacrylate (PETEA) chains, pentaerythritol triacrylate chains, ethoxylated trimethylolpropane triacrylate (ETPTA) chains, ethylene It comprises lightly crosslinked network polymer chains selected from glycol methyl ether acrylate (EGMEA) chains, or combinations thereof.

Typically, the high modulus polymer is originally in a monomeric or oligomeric state that can be cured to form a highly modulus crosslinked polymer. Prior to curing, these polymers or oligomers are soluble in organic solvents to form a polymer solution. Particles of cathode active material (for example, sulfur-carbon hybrid particles, sulfur-graphite hybrid particles, sulfur-graphene hybrid particles, sulfur compound particles, metal sulfide particles, etc.) are dispersed in this polymer solution, and the active material particles-polymer ( A suspension (dispersion or slurry) of the monomer or oligomer) mixture can be formed. This suspension can then be subjected to a solvent removal process while the individual particles remain substantially separated from each other. Polymers (or monomers or oligomers) precipitate and are deposited on the surface of these active material particles. This can be accomplished, for example, by spray drying, ultrasonic atomization, air-assisted atomization, aerosolization, and other secondary particle formation procedures.

を有する。 For example, ethoxylated trimethylopropane triacrylate monomer (ETPTA, Mw=428, chemical formula below) can be dissolved in an organic solvent such as ethylene carbonate (EC) or diethyl carbonate (DEC), along with an initiator. Anode active material particles (such as Si, Sn, SnO ₂ , and Co ₃ O ₄ particles) can then be dispersed in the ETPTA monomer/solvent/initiator solution to form a slurry, which can be spray-dried to form an ETPTA Monomer/initiator encapsulated anode particles can be formed. These encapsulated anode particles can then be thermally cured to obtain microparticles consisting of anode particles encapsulated with a thin layer of high modulus polymer. The polymerization and crosslinking reactions of the monomers can be initiated by radical initiators derived from benzoyl peroxide (BPO) or AIBN by thermal decomposition of the initiator molecules. ETPTA monomer has the following chemical formula

has.

As another example, high modulus polymers in encapsulation can be based on cationic polymerization and crosslinking of cyanoethyl polyvinyl alcohol (PVA-CN, formula 2) in succinonitrile (SN).

The procedure can begin by dissolving PVA-CN in succinonitrile (NCCH ₂ CH ₂ CN) to form a mixed solution. Then, the initiator is added to the mixed solution. For example, LiPF ₆ can be added to a PVA-CN/SN mixed solution in a weight ratio (selected from a preferred range of 20:1 to 2:1) to form a precursor solution. Particles of the selected anode active material are then introduced into the mixed solution to form a slurry. The slurry can then be subjected to a microencapsulation procedure to produce anode active material particles coated with an encapsulated layer of the reactive mass, PVA-CN/LiPF ₆ . These wrapped particles can then be heated at a temperature (eg, 75-100° C.) for 2-8 hours to obtain high modulus polymer encapsulated anode active material particles. During this process, cationic polymerization and crosslinking of cyano groups in PVA-CN can be initiated by PF ₅ derived from the thermal decomposition of LiPF ₆ at such high temperatures.

It is essential that these materials form a lightly crosslinked network of polymer chains. In other words, the network polymer or crosslinked polymer must have a relatively low degree of crosslinking or low crosslink density in order to impart high elastic deformation.

The crosslink density of a crosslinked network of polymer chains can be defined as the reciprocal of the molecular weight (Mc) between the crosslinks. The crosslink density can be determined by the equation, Mc=ρRT/Ge, where Ge is the equilibrium modulus determined by the temperature sweep of dynamic mechanical analysis, ρ is the physical density, and R is J/mol ^* is the universal gas constant in K and T is the absolute temperature in K. Once Ge and ρ are determined experimentally, Mc and crosslink density can be calculated.

The magnitude of Mc is normalized by dividing the Mc value by the molecular weight of the characteristic repeating unit of the crosslink or chain linkage, yielding Nc, which is the number of repeating units between two crosslinking points. It was found that the elastic deformation strain correlates very well with Mc and Nc. The elasticity of crosslinked polymers comes from the large number of repeating units (large Nc) between the crosslinks. The repeating unit can assume a more relaxed conformation (eg, a random coil) when the polymer is unstressed. However, when mechanical stress is applied to the polymer, the bonded chains unwind or elongate, resulting in large deformations. Longer bond chains (larger Nc) between cross-linking points allow for greater elastic deformation. When the load is released, the bonded chain returns to a more relaxed or coiled state. During mechanical loading of the polymer, crosslinking prevents the chains from slipping, which would otherwise form plastic deformations (irrecoverable).

Preferably, the Nc value of the high modulus polymer is greater than 5, more preferably greater than 10, even more preferably greater than 100, and even more preferably greater than 200. These Nc values are achieved by using different crosslinking agents with different functionalities and by designing the polymerization and crosslinking reactions to proceed at different temperatures and for different periods of time to achieve different elastic deformation values. Therefore, it can be easily controlled and varied.

Alternatively, the degree of crosslinking can be determined using the Mooney-Rilvin method. Crosslinking can also be measured by swelling experiments. In swelling experiments, a crosslinked sample is placed in a good solvent for the corresponding linear polymer at a specific temperature and the change in mass or volume is measured. The higher the degree of crosslinking, the less swelling. Based on the degree of swelling, the Flory interaction parameters (Flory-Huggins Eq., which are related to the interaction of the solvent with the sample), and the density of the solvent, the theoretical The degree of crosslinking can be calculated. The Flory-Rehner equation can be useful in determining crosslinking.

Highly modulus polymers in encapsulation can include simultaneous interpenetrating network (SIN) polymers in which two cross-linked chains are intertwined with each other, or semi-interpenetrating network polymers (semi-IPN) that include a cross-linked polymer and a linear polymer. An example of a semi-IPN is a UV curable/polymerizable tri/monoacrylate mixture consisting of ethoxylated trimethylolpropane triacrylate (ETPTA) and ethylene glycol methyl ether acrylate (EGMEA) oligomers. ETPTA is a photo (UV) crosslinkable monomer with a trivalent vinyl group and can form a network of crosslinked chains. Furthermore, EGMEA having a monovalent vinyl group can be UV polymerized and becomes a highly flexible linear polymer due to the presence of oligomeric ethylene oxide units. When the degree of crosslinking of ETPTA is moderate or low, the resulting ETPTA/EGMEA semi-IPN polymer provides good mechanical flexibility or elasticity and reasonable mechanical strength. The lithium ion conductivity of this polymer typically ranges from 10 ⁻⁴ to 5×10 ⁻³ S/cm.

The highly elastic polymer may form a mixture or blend with a conductive polymer selected from polyaniline, polypyrrole, polythiophene, polyfuran, bicyclic polymers, derivatives thereof (e.g., sulfonated versions), or combinations thereof. can.

In some embodiments, the high modulus polymer is poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), polyvinylidene fluoride (PVdF), Polybis-methoxyethoxyethoxide-phosphazenex, polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), derivatives thereof (such as sulfonated versions), or combinations thereof A mixture may be formed with a lithium ion conductive polymer selected from:

High modulus polymers can form polymer blends with conventional elastomers or rubbers. Unsaturated rubbers that can be vulcanized into elastomers include natural polyisoprene (e.g. cis-1,4-polyisoprene natural rubber (NR) and trans-1,4-polyisoprene gatta-percha), synthetic polyisoprene (IR for isoprene rubber), polybutadiene (BR for butadiene rubber), chloroprene rubber (CR), polychloroprene (e.g. neoprene, vaprene, etc.), halogenated butyl rubber (including chlorobutyl rubber (CIIR) and bromobutyl rubber (BIIR)) (copolymer of isobutylene and isoprene, IIR), styrene-butadiene rubber (copolymer of styrene and butadiene, SBR), and nitrile rubber (copolymer of butadiene and acrylonitrile, NBR).

Some elastomers are saturated rubbers that cannot be cured by sulfur vulcanization and are made into rubbery or elastomeric materials by various means, for example, by having copolymer domains that hold together other linear chains. be done. Each of these elastomers can be prepared by several means: melt mixing (e.g., followed by pelletization and ball milling), solution mixing (with or without organic solvents, uncured polymer) followed by drying (e.g., spray drying). used to encapsulate particles of anode active material by one of the following: (dissolution of anode active material particles in monomers, monomers, or oligomers), surface active polymerization, or in situ polymerization of an elastomer in the presence of anode active material particles. can.

Saturated rubbers and related elastomers in this category include EPM (ethylene propylene rubber, a copolymer of ethylene and propylene), EPDM rubber (ethylene propylene diene rubber, a terpolymer of ethylene, propylene and diene components), epichlorohydrin rubber (ECO ), polyacrylic rubbers (ACM, ABR), silicone rubbers (SI, Q, VMQ), fluorosilicone rubbers (FVMQ), fluoroelastomers (FKM, and FEPM, Viton, Tecnoflon, Fluorel, Aflas, and Dai-El, etc.) , bellfluoroelastomers (FFKM: Tecnoflon PFR, Kalrez, Chemraz, Perlast), polyether block amide (PEBA), chlorosulfonated polyethylene (CSM, e.g. Hypalon), and ethylene vinyl acetate (EVA), thermoplastic elastomers (TPE) , the protein resilin, and the protein elastin. Polyurethanes and their copolymers (eg, urea-urethane copolymers) are particularly useful elastomeric shell materials for encapsulating anode active material particles.

C. Encapsulation of Cathode Active Material Particles with Highly Elastic Polymers Some microencapsulation processes require that highly elastic polymers or their precursors (monomers or oligomers) be soluble in a solvent. Fortunately, all high modulus polymers or precursors thereof used herein are soluble in several common solvents. The uncured polymer or its precursor can be easily dissolved in common organic solvents to form a solution. This solution can then be used to encapsulate solid particles via several microencapsulation methods described below. Upon encapsulation, the polymer shell then polymerizes and crosslinks.

There are three broad categories of microencapsulation methods that can be performed to produce highly elastic polymer-encapsulated particles of cathode active material: physical methods, physicochemical methods, and chemical methods. Physical methods include pan coating, air suspension coating, centrifugal extrusion, vibrating nozzles, and spray drying methods. Physicochemical methods include ion channel gelation method and coacervation phase separation method. Chemical methods include interfacial polycondensation, interfacial crosslinking, in situ polymerization, and matrix polymerization.

Pan Coating Method: The pan coating process involves coating the active material in a pan or similar device until the encapsulation material (e.g., monomer/oligomer, polymer melt, polymer/solvent solution) reaches the desired encapsulation shell thickness. Involves rotating particles.

Air Suspension Coating Method: In the air suspension coating process, solid particles (core material) are dispersed in a supporting air stream within an encapsulation chamber. A controlled flow of a polymer-solvent solution (polymer or its monomers or oligomers dissolved in the solvent, or only its monomers or oligomers in liquid state) is simultaneously introduced into this chamber and the solution impinges on the suspended particles. Allow coating. These suspended particles are encapsulated (completely coated) with polymer or its precursor molecules while the volatile solvent is removed, and a very thin layer of polymer (or subsequently cured/coated) is applied to the surface of these particles. A layer of its precursor) remains that is cured. This process can be repeated several times until the required parameters such as complete coating thickness (ie, encapsulation shell or wall thickness) are achieved. Also, the airflow supporting the particles helps dry the particles, and the drying rate is directly proportional to the temperature of the airflow and can be adjusted to optimize the shell thickness.

In a preferred embodiment, the particles of the encapsulation zone portion can be subjected to recirculation for repeated coatings. Preferably, the encapsulation chamber is arranged such that the particles pass upwardly through the encapsulation zone, are then dispersed in the slowly moving air, and sink to the bottom of the encapsulation chamber to achieve the desired encapsulation shell thickness. The particles are allowed to pass through the encapsulation zone repeatedly until

Centrifugal extrusion: Active material particles can be encapsulated using a rotating extrusion head containing concentric nozzles. In this process, a stream of core fluid (a slurry containing particles of material dispersed in a solvent) is surrounded by a shell solution or sheath of melt. As the instrument rotates and the flow moves through the air, the Rayleigh instability causes it to collapse into core droplets, each coated with shell solution. During the flight of the droplet, the molten shell may harden or the solvent may evaporate from the shell solution. If desired, the capsules can be hardened after formation by trapping them in a hardening bath. This process is only suitable for liquids or slurries since droplets are formed by the collapse of a liquid stream. A high production rate can be achieved. Up to 22.5 kg of microcapsules can be produced per nozzle per hour, and extrusion heads containing 16 nozzles are readily available.

Vibrating nozzle method: Core-shell or matrix encapsulation of active materials can be performed using laminar flow through the nozzle and vibration of the nozzle or liquid. The oscillations need to be done in sync with the Rayleigh instability, resulting in very uniform droplets. The liquid can consist of any liquid of limited viscosity (1 to 50,000 mPa·s): an emulsion, suspension, or slurry containing the active material. Solidification can be carried out according to the gelling system used for internal gelling (eg sol-gel processing, melting) or external gelling (eg additional binder system in the slurry).

Spray Drying: Spray drying can be used to encapsulate particles of active material when the active material is dissolved or suspended in a melt or polymer solution. In spray drying, a liquid feedstock (solution or suspension) is atomized to form droplets that, upon contact with hot gas, evaporate the solvent and a thin polymeric shell completely envelops the solid particles of active material.

Coacervation phase separation: This process consists of three steps carried out under continuous stirring.
(a) Formation of three immiscible chemical phases: a liquid making vehicle phase, a core material phase, and an encapsulating material phase. The core material is dispersed in a solution of the encapsulating polymer (or its monomers or oligomers). The encapsulating material phase, which is an immiscible polymer in a liquid state, is removed by (i) a change in the temperature of the polymer solution, (ii) the addition of a salt, (iii) the addition of a non-solvent, or (iv) the presence of incompatible polymers in the polymer solution. Formed by addition.
(b) Deposition of encapsulating shell material: core material dispersed in an encapsulating polymer solution, encapsulation of the polymeric material coated around the core particles, and adsorbed on the interface formed between the core material and the vehicle phase. Deposition of liquid polymer wrapped around the core particle by the polymer.
(c) Curing of the encapsulation shell material: The shell material is immiscible in the vehicle phase and becomes rigid through heat, cross-linking, or melting techniques.

Interfacial polycondensation and crosslinking: Interfacial polycondensation involves introducing two reactants into contact at an interface where they react with each other. It is based on the concept of the Schotten-Baumann reaction between acid chlorides and compounds containing active hydrogen atoms (such as amines or alcohols), polyesters, polyureas, polyurethanes, or urea-urethane condensations. Under appropriate conditions, a thin, flexible encapsulation shell (wall) rapidly forms at the interface. A solution of the active material and diacid chloride is emulsified in water and an aqueous solution containing the amine and polyfunctional isocyanate is added. A base can be added to neutralize the acid formed during the reaction. A condensed polymer shell forms instantly at the interface of the emulsion droplets. Interfacial crosslinking originates from interfacial polycondensation, where crosslinking occurs between growing polymer chains and polyfunctional chemical groups to form an elastomeric shell material.

In situ polymerization: In some microencapsulation processes, active material particles are first completely coated with monomers or oligomers. Direct polymerization and crosslinking of monomers or oligomers is then carried out on the surface of these material particles.

Matrix polymerization: This method involves dispersing and embedding a core material in a polymer matrix during particle formation. This can be accomplished by spray drying, where the particles are formed by evaporation of the solvent from the matrix material. Another possible route is the concept that solidification of the matrix is caused by chemical changes.

D. Further details about the encapsulated particulates, cathode layer, and structure of Li-S, Na-S, and K-S cells The anode active material layer of the alkali metal-sulfur cell is similar to that of the prior art Li-S cell. As shown in the left part of FIG. 1(A), it may include a Li, Na, or K foil or coating supported by a current collector (eg, a Cu foil). Alternatively, the anode active material may include particles of prelithiated Si particles or surface-stabilized Li particles, for example, as shown in the left part of FIG. 1(B). However, as already explained above, the cathode layer of this cell is different.

The electrolyte in an alkali metal-sulfur cell can be an organic electrolyte, an ionic liquid electrolyte, a gel polymer electrolyte, a solid electrolyte (eg, a polymer solid electrolyte or an inorganic solid electrolyte), a quasi-solid electrolyte, or a combination thereof. The electrolyte typically includes an alkali metal salt (lithium, sodium, and/or potassium salt) dissolved in a solvent.

The solvents are 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DEGDBE), 2-ethoxy Ethyl ether (EEE), sulfone, sulfolane, ethylene carbonate (EC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), ethyl propionate, methyl propionate, propylene carbonate (PC), γ -Butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, xylene, methyl acetate (MA), fluoroethylene carbonate (FEC), vinylene carbonate (VC), allyl ethyl carbonate (AEC), hydrofluoroethers, room temperature ionic liquid solvents, or combinations thereof.

Electrolyte salts incorporated into the non-aqueous electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and trifluoromethane. Lithium sulfonate (LiCF ₃ SO ₃ ), lithium bis-trifluoromethylsulfonylimide [LiN(CF ₃ SO ₂ ) ₂ ], lithium bis(oxalato)borate (LiBOB), lithium oxalyl difluoroborate (LiBF ₂ C ₂ O ₄ ), lithium oxalyl difluoroborate (LiBF ₂ C ₂ O ₄ ), lithium nitrate (LiNO ₃ ), Li-fluoroalkyl-phosphoric acid (LiPF ₃ (CF ₂ CF ₃ ) ₃ ), lithium bisperfluoroethylsulfonylimide (LiBETI) , ionic liquid salts, sodium perchlorate (NaClO ₄ ), potassium perchlorate (KClO ₄ ), sodium hexafluorophosphate (NaPF ₆ ), potassium hexafluorophosphate (KPF ₆ ), sodium borofluoride (NaBF ₄ ) , potassium borofluoride (KBF ₄ ), sodium hexafluoroarsenide, potassium hexafluoroarsenide, sodium trifluorometasulfonate (NaCF ₃ SO ₃ ), potassium trifluoromethanesulfonate (KCF ₃ SO ₃ ), bistrifluoromethylsulfonyl It can be selected from lithium salts such as sodium imide (NaN(CF ₃ SO ₂ ) ₂ ), sodium trifluoromethanesulfonimide (NaTFSI), and potassium bis-trifluoromethylsulfonylimide (KN(CF ₃ SO ₂ ) ₂ ). Among these, LiPF ₆ , LiBF ₄ , and LiN(CF ₃ SO ₂ ) _{2 are} preferred for Li-S cells, NaPF ₆ and LiBF ₄ are preferred for Na-S cells, and KBF ₄ is preferred for KS cells. The content of the electrolyte salt in the non-aqueous solvent is preferably from 0.5 to 3.0 M (mol/L) on the cathode side and from 3.0 to >10 M on the anode side.

Ionic liquids are composed only of ions. Ionic liquids are low melting temperature salts that become molten or liquid when a desired temperature is exceeded. For example, a salt is considered an ionic liquid if its melting point is less than 100°C. If the melting temperature is below room temperature (25°C), the salt is called a room temperature ionic liquid (RTIL). IL salts are characterized by weak interactions due to the combination of large cations and charge delocalized anions. This reduces the tendency to crystallize due to flexibility (anion) and asymmetry (cation).

The combination of the 1-ethyl-3-methyl-imidazolium (EMI) cation and the N,N-bis(trifluoromethane)sulfonamide (TFSI) anion produces a typical well-known ionic liquid. This combination results in a fluid with ionic conductivity comparable to many organic electrolyte solutions, as well as low decomposition and low vapor pressure up to about 300-400°C. This suggests an electrolyte that is generally less volatile and non-flammable, and therefore much safer for batteries.

Ionic liquids are essentially composed of organic ions that, due to the ease of preparation of a variety of components, give rise to an essentially unlimited number of structural changes. Therefore, different types of salts can be used to design ionic liquids with desired properties for a given application. These include imidazolium, pyrrolidinium, and quaternary ammonium salts as cations, and bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, and hexafluorophosphate as anions, among others. Useful ionic liquid-based sodium salts (not solvents) consist of sodium ion as the cation and bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, or hexafluorophosphate as the anion. be able to. Based on their composition, ionic liquids are classified into various classes, including aprotic, protic, and zwitterionic types, each of which is suitable for specific applications.

Common cations for room temperature ionic liquids (RTILs) include, but are not limited to, tetraalkylammonium, di-, tri-, and tetra-alkylimidazolium, alkylpyridinium, dialkylpyrrolidinium, dialkylpiperidinium, tetra- Mention may be made of alkylphosphoniums as well as trialkylsulfoniums. Common anions for RTIL include, but are not limited to, BF ₄ ⁻ , B(CN) ₄ ⁻ , CH ₃ BF ₃ ⁻ , CH2CHBF ₃ ⁻ , CF ₃ BF ₃ ⁻ , C ₂ F ₅ BF ₃ ⁻ , n -C ₃ F ₇ BF ₃ ^- , n-C ₄ F ₉ BF ₃ ^- , PF ₆ ^- , CF ₃ CO ₂ ^- , CF ₃ SO ₃ ^- , N(SO ₂ CF ₃ ) ₂ ^- , N(COCF ₃ ) (SO ₂ CF ₃ ) ⁻ , N(SO ₂ F) ₂ ⁻ , N(CN) ₂ ⁻ , C(CN) ₃ ⁻ , SCN ⁻ , SeCN ⁻ , CuCl ₂ ⁻ , AlCl ₄ ⁻ , F(HF) _{2 .3} ^- etc. Relatively speaking, imidazolium- or sulfonium-based cations and AlCl ₄ ⁻ , BF ₄ ⁻ , CF ₃ CO ₂ ⁻ , CF ₃ SO ₃ ⁻ , NTf ₂ ⁻ , N(SO ₂ F) ₂ ⁻ , or F Combination with complex halide anions such as (HF) _2.3 ^- results in RTILs with good operating conductivity.

RTILs have high intrinsic ionic conductivity, high thermal stability, low volatility, low (virtually zero) vapor pressure, non-flammability, and the ability to remain liquid over a wide temperature range above and below room temperature. can have typical properties such as high polarity, high viscosity, and wide electrochemical window. These properties, with the exception of high viscosity, are desirable properties when using RTIL as an electrolyte component (salt and/or solvent) in Li-S cells.

In the products of the invention (including an alkali metal cell, a cathode active layer, and a cathode active material powder), the core material (encapsulated with a thin layer of high modulus polymer) is a sulfur-carbon hybrid, a sulfur-graphite hybrid , sulfur-graphene hybrids, conductive polymer-sulfur hybrids, metal sulfides, sulfur compounds, etc. These hybrid or compound materials are made in the form of particles comprising mixtures, blends, composites, or bound objects of sulfur or sulfide and carbon, graphite, graphene, or conductive polymeric materials. Metal sulfides (eg, lithium polysulfide, sodium polysulfide, etc.) and sulfur compounds are readily available in particulate form. Sulfur can be combined with conductive materials (carbon, graphite, graphene, and/or conductive polymers) to form composites, mixtures, or bound objects (eg, sulfur bound to a graphene oxide surface).

There are many well-known procedures that can be used to particulate the aforementioned sulfur-containing materials. For example, solid sulfur can be mixed with carbon or graphite materials to form composite particles using ball milling. The resulting particles are typically oval or potato-shaped with a size of 1-20 μm. Also, vapor phase infiltration, solution infiltration, chemical infiltration, or electrochemical infiltration is used to infiltrate S or sulfide into the pores of porous carbon or graphite particles (e.g., activated carbon, mesoporous carbon, activated carbon fibers, etc.) be able to. Alternatively, these S-coated materials can be prepared by depositing sulfur on the surface of graphene sheets, CNTs, carbon nanofibers, etc., and then using high-intensity ball milling, spray drying (of suspensions), aerosol formation, etc. The nanomaterials can be formed into spherical or elliptical shapes. These particles are then encapsulated with a high modulus polymer using the microencapsulation process described above.

Conventional Li-S cell cathodes typically have less than 70% sulfur by weight in a composite cathode consisting of sulfur and conductive additive/support. Even when the sulfur content of prior art composite cathodes reaches or exceeds 70% by weight, the specific capacity of the composite cathode is typically significantly lower than that expected based on theoretical predictions. For example, the theoretical specific capacity for sulfur is 1,675 mAh/g. A composite cathode consisting of 70% sulfur (S) and 30% carbon black (CB) with no binder should be able to store up to 1,675 x 70% = 1,172 mAh/g. Unfortunately, the observed specific capacities are typically less than 75% or 879 mAh/g of what can be achieved (in this example often less than 50% or 586 mAh/g). In other words, the utilization rate of the active material (S) is typically less than 75% (or less than 50%). This is a major problem in the prior art of Li-S cells, and there has been no solution to this problem.

Therefore, it is very advantageous to obtain high sulfur loading and at the same time maintain ultra-thin/small thickness/diameter of sulfur in order to significantly improve sulfur utilization efficiency, energy density, and power density. be. For example, nanoscale sulfur (1-5 nm thick) can be deposited on graphene surfaces using chemistry, electrochemistry, or vapor deposition to form S-coated or S-bonded graphene sheets. These S-coated or S-bonded graphene sheets are then agglomerated together using tumbling mixing, ball milling, or spraying procedures. These steps allow the preparation of S conductive material hybrids containing 85% to 99% sulfur while maintaining the coating thickness or particle size between 1 nm and 5 nm. This ultra-small size allows fast lithium diffusion and lithium-sulfur reactions, resulting in high S utilization efficiency (and thus high energy density) even at high charge/discharge rates. By implementing highly elastic polymers around these hybrid particles or sulfur compound/sulfide particles, we have significantly reduced and even eliminated the shuttle effect, resulting in alkali metal batteries with long cycle life.

Again, the shuttle effect is related to the tendency of sulfur or alkali metal polysulfides forming at the cathode to dissolve in the solvent and the tendency of dissolved lithium polysulfide species to migrate from the cathode to the anode, where lithium and reacts to form species that prevent sulfide from returning to the cathode during subsequent discharge operations of the Li-S cell (detrimental shuttle effect). Wrapping the high modulus polymer appears to effectively trap the sulfur and metal polysulfides therein, thereby preventing or reducing such dissolution and migration problems. We have solved the most important and long-standing problem of alkali metal-sulfur batteries.

The cathode active material layer may further include a binder resin that binds the plurality of particulates (of encapsulated sulfur-containing particles) together to form the cathode active material layer. In the cathode active material layer described above, the binder resin is not part of the plurality of fine particles (that is, not included inside the core portion of the fine particles), but is outside the plurality of fine particles. The high modulus polymer does not enclose the binder resin, and the binder resin is not embedded in the high modulus polymer.

In another construction, the cathode active material layer of a rechargeable alkali metal-sulfur cell may include a resin binder, an optional conductive additive, and a plurality of particles of a sulfur-containing material, where the binder resin is a sulfur-containing material. It helps bind the contained particles together, forming a solid layer of structural integrity. This solid layer can be supported by a cathode current collector (eg Al foil). This solid layer is covered and protected with a layer of high modulus polymer.

In this solid layer, the sulfur-containing material is selected from sulfur-carbon hybrids, sulfur-graphite hybrids, sulfur-graphene hybrids, conductive polymer-sulfur hybrids, metal sulfides, sulfur compounds, or combinations thereof. Again, more specifically, the sulfur-containing material particles are bound together by a resin binder to form an integrated solid layer (a layer of adequate structural integrity to be self-supporting), without additives or reinforcements. A thin layer of highly elastic polymer with a recoverable tensile strain of greater than 10% when measured, a lithium ion conductivity of greater than 10 ⁻⁵ S/cm at room temperature, and a thickness of 0.5 nm to 10 μm creates an integrated solid state. The layers are covered and protected. The integrated solid layer can be bonded to the cathode current collector by a resin binder.

Such a high modulus polymeric protective layer can be formed by spraying a precursor mass (monomer or oligomer with the necessary initiator or curing agent) over a prefabricated cathode active material layer, followed by polymerization and crosslinking. .

The invention also provides a rechargeable alkali metal-sulfur cell comprising such a cathode active material layer, where the entire layer is covered and protected with a high modulus polymer. The alkali metal-sulfur cell includes (a) an anode active material layer and an optional anode current collector supporting the anode active material layer; (b) a cathode including the cathode active material layer; and (c) an anode active material layer. an electrolyte with an optional porous separator layer in ionic contact with the material layer and the cathode active material layer. Advantageously, this high modulus polymer protective layer is implemented between the cathode active layer and the porous separator.

In all versions of the alkali metal-sulfur cells described above, the anode active material may include, by way of example, a lithium metal foil or a large capacity of Si, Sn, or SnO ₂ that can store large amounts of lithium. The cathode active material may include pure sulfur (if the anode active material includes lithium), lithium polysulfide, or optional sulfur-containing compounds, molecules, or polymers. If the cathode active material includes a lithium-containing species (e.g., lithium polysulfide) during cell fabrication, the anode active material can be any material capable of storing large amounts of lithium (e.g., Si, Ge, Sn, SnO2 _, etc.) It can be.

On the anode side, if lithium metal is used as the only anode active material in a Li-S cell, there is a concern about the formation of lithium dendrites, which can cause internal short circuits and thermal runaway. Herein, two approaches were used separately or in combination to address this dendrite formation problem. One involves the use of highly concentrated electrolytes on the anode side, and the other involves the use of nanostructures consisting of conductive nanofilaments. In the latter case, multiple conductive nanofilaments are processed to form an integrated cohesive structure, preferably in the form of a dense web, mat, or paper, such that the filaments intersect, overlap, or in some way intersect with each other. (e.g., using a binder material) to form a network of electronically conductive paths. The integrated structure has substantially interconnected pores to accommodate the electrolyte. Nanofilaments include, for example, carbon nanofibers (CNFs), graphite nanofibers (GNFs), carbon nanotubes (CNTs), metal nanowires (MNWs), conductive nanofibers obtained by electrospinning, and conductive electrospun composite nanofibers. It can be selected from fibers, nanoscaled graphene platelets (NGP), or combinations thereof. The nanofilaments can be bound by a binder material selected from polymers, coal tar pitch, petroleum pitch, mesophase pitch, coke, or derivatives thereof.

The nanofibers are from the group consisting of conductive electrospun polymer fibers, electrospun polymer nanocomposite fibers containing conductive fillers, nanocarbon fibers obtained from carbonization of electrospun polymer fibers, electrospun pitch fibers, and combinations thereof. can be selected. For example, nanostructured electrodes can be obtained by electrospinning polyacrylonitrile (PAN) into polymer nanofibers followed by carbonization of the PAN. Note that some of the pores in the carbonized structure are larger than 100 nm and some are smaller than 100 nm.

The cathode active layer of the present invention can be incorporated into one of at least four broad classes of rechargeable lithium metal cells (or similarly, in sodium metal or potassium metal cells):
(A) Lithium metal-sulfur with conventional anode configuration: The cell includes an optional cathode current collector, a cathode layer of the present invention, a separator/electrolyte, and an anode current collector. Potential dendrite formation can be overcome by using a highly concentrated or solid electrolyte at the anode.
(B) Lithium metal-sulfur battery with a nanostructured anode configuration: the cell comprises an optional cathode current collector, a cathode of the invention, a separator/electrolyte, an optional anode current collector, and during charging or recharging operation. contains nanostructures housing lithium metal that are deposited on the anode. This nanostructure of nanofilaments (web, mat, or paper) provides a uniform electric field that allows uniform lithium metal deposition and reduces the tendency to form dendrites. This configuration can provide dendrite-free cells for long and safe cycling behavior.
(C) Lithium ion-sulfur cell with conventional anode: For example, the cell includes an anode consisting of anode-active graphite particles bound with a binder such as polyvinylidene fluoride (PVDF) or styrene butadiene rubber (SBR). The cell also includes a cathode current collector, a cathode of the invention, a separator/electrolyte, and an anode current collector.
(D) Lithium ion-sulfur cell with nanostructured anode: For example, the cell comprises a web of nanofibers coated with a Si coating or bonded with Si nanoparticles. The cell also includes an optional cathode current collector, a cathode of the invention, a separator/electrolyte, and an anode current collector. This configuration provides ultra-high capacity, high energy density, and safe and long cycle life.

In a lithium-ion sulfur cell (e.g., as described in (C) and (D) above), the anode active materials include (a) silicon (Si), germanium (Ge), tin (Sn), lead (Pb); , antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), titanium (Ti), iron (Fe), and cadmium (Cd). ), and lithiated versions thereof; (b) alloys or intermetallic compounds with other elements of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, or Cd; and lithiated versions thereof; (c) Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ni, Co, Ti, Mn. or Cd, and oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides of these mixtures or complexes, and lithiated versions thereof; (d) salts and hydroxides of Sn; , and lithiated versions thereof, (e) carbon or graphite materials and prelithiated versions thereof, and combinations thereof. Non-lithium ionized versions can be used when the cathode side includes lithium polysulfide or other lithium sources during cell fabrication.

Contemplated lithium metal cells include an anode current collector, an electrolyte phase (optionally but preferably supported by a porous separator, such as a porous polyethylene-polypropylene copolymer film), a cathode of the invention, and an optional cathode. It can consist of a current collector.

For sodium ion-sulfur cells or potassium ion-sulfur cells, the anode active material layer may include an anode active material selected from the group consisting of: (a) silicon (Si) doped with sodium or potassium, germanium; (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), titanium (Ti), cobalt (Co), nickel (Ni), manganese (Mn), cadmium (Cd), and mixtures thereof, (b) Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof; potassium-containing alloys or intermetallic compounds, (c) sodium or potassium of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or complexes thereof; Containing oxides, carbides, nitrides, sulfides, phosphides, selenides, tellurides, or antimonides, (d) sodium or potassium salts, (e) graphite particles, hard carbon, soft carbon or carbon particles, and Presodiumized versions of these (predoped or preloaded with Na), as well as combinations thereof.

The following examples are presented primarily for the purpose of illustrating the best mode of practicing the invention and should not be construed as limiting the scope of the invention.

Example 1: Highly Elastic Polymer Derived from Ethoxylated Trimethylpropane Triacrylate Monomer In a typical procedure, ethoxylated trimethylpropane triacrylate monomer (ETPTA, Mw=428, Sigma-Aldrich) was prepared at 3/97 (w/w). was dissolved in a solvent mixture of ethylene carbonate (EC)/diethyl carbonate (DEC) in a composition ratio based on the weight of ETPTA/solvent. Then, benzoyl peroxide (BPO, 1.0% by weight based on ETPTA content) was added as a radical initiator to enable the thermal crosslinking reaction after mixing with the cathode particles. Cathode active material particles (e.g., S-graphene particles) are then dispersed in the ETPTA monomer/solvent/initiator solution to form a slurry, which is spray dried to form the S-graphene encapsulated with ETPTA monomer/initiator. Particles were formed. These wrapped particles were then thermally cured at 60° C. for 30 minutes to obtain microparticles consisting of S-graphene particles encapsulated with a thin layer of high modulus polymer. The thickness of the ETPTA polymer shell varied from 1.3 nm to 115 nm.

Separately, a portion of the ETPTA monomer/solvent/initiator solution was cast onto a glass surface to form a wet film, which was heat dried and then cured at 60° C. for 30 minutes to form a film of crosslinked polymer. . In this experiment, the BPO/ETPTA weight ratio was varied from 0.1% to 4% and the degree of crosslinking of several different polymer films was varied. As a means of characterizing the degree of crosslinking, a portion of the cured polymer sample was subjected to dynamic mechanical testing to determine the number average molecular weight (Mc) between two crosslinking points and the corresponding number of repeating units (Nc); Equilibrium dynamic elastic modulus Ge was obtained.

Several tensile specimens were cut from each crosslinked film and tested on a standard testing machine. Representative tensile stress-strain curves for four BPO-initiated and cross-linked ETPTA polymers are shown in Figure 5, indicating that this series of network polymers has elastic deformations of approximately 230% to 700%. . These data relate to pure polymer without additives. Addition of up to 30% by weight of lithium salt typically reduces this elasticity to a reversible tensile strain of 10% to 100%.

Thin films (1 nm to 10 μm) of such polymers can be implemented between the porous separator and the cathode active material layer.

Example 2: Preparation of a Highly Elastic Polymer Derived from Cyano-Ethyl Polyvinyl Alcohol A highly elastic polymer for encapsulating some sulfur-based and lithium polysulfide-based cathode particles is cyanoethyl polyvinyl alcohol (PVA) in succinonitrile (SN). -CN) based on cationic polymerization and crosslinking. The procedure began by dissolving PVA-CN in succinonitrile to form a mixed solution. After this step, an initiator was added to the solution. We chose to use _LiPF6 as an initiator in order to incorporate some lithium species into the high modulus polymer. The ratio of LiPF ₆ and PVA-CN/SN mixed solution was varied from 1/20 to 1/2 by weight to form a series of precursor solutions. Selected cathode active materials and particles of this graphene-encased version were then introduced into these solutions to form a series of slurries. The slurry was then individually subjected to a microencapsulation procedure to produce cathode active material particles coated on their entire outer surface with an encapsulated layer of the reactive mass, PVA-CN/LiPF ₆ . These wrapped particles were then heated at a temperature of 75-100° C. for 2-8 hours to obtain active material particles encapsulated with high modulus polymer.

Separately, the reaction mass, PVA-CN/LiPF ₆ , was cast on the glass surface to form several films, which were polymerized and cured to obtain crosslinked polymers with different degrees of crosslinking. Tensile tests were also performed on these films and some test results are summarized in FIG. This series of crosslinked polymers can be elastically stretched from about 80% (higher degree of crosslinking) to 400% (lower degree of crosslinking). A thin film (1 nm to 10 μm) of such a polymer can be implemented between the porous separator and the cathode active material layer.

Example 3: Preparation of Highly Elastic Polymers Derived from Pentaerythritol Tetraacrylate Pentaerythritol tetraacrylate (PETEA), Formula 3, was used as the monomer for encapsulation of sulfur-carbon, sulfur-graphite, and sulfur-polymer hybrid particles. .

The precursor solution is typically 1.5% by weight PETEA (C ₁₇ H ₂₀ O ₈ ) monomer and a solvent mixture of 1,2-dioxolane (DOL)/dimethoxymethane (DME) (1:1 by volume). ) of azodiisobutyronitrile (AIBN, C ₈ H ₁₂ N ₄ ) initiator. Hybrid particles of different sulfur systems were added to the precursor solution and encapsulated in a thin layer of PETEA/AIBN/solvent precursor solution by spray drying method (some solvent evaporated, but some remained). The precursor solution was polymerized and cured at 70° C. for 30 minutes to obtain microparticles consisting of particles encapsulated with a highly elastic polymer.

The reaction mass, PETEA/AIBN (without cathode particles), was cast on the glass surface to form several films, which were polymerized and cured to obtain crosslinked polymers with different degrees of crosslinking. Tensile tests were also performed on these films and some test results are summarized in FIG. This series of crosslinked polymers can be elastically stretched from about 25% (higher degree of crosslinking) to 80% (lower degree of crosslinking). A thin film (1 nm to 10 μm) of such a polymer can be implemented between the porous separator and the cathode active material layer.

Example 4: Preparation of ETPTA-based Highly Elastic Semi-IPN Polymers In the encapsulation of various anode particles with ETPTA semi-IPN polymers, ETPTA (Mw = 428 g/mol, trivalent acrylate monomer), EGMEA (Mw = 482 g/mol, monomer) acrylate oligomer) and 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP, photoinitiator) were dissolved in a solvent (propylene carbonate, PC) to form a solution. The weight ratio of HMPP and ETPTA/EGMEA mixture was varied from 0.2% to 2%. The proportion of ETPTA/EGMEA in the solution was varied from 1% to 5% to produce different encapsulation layer thicknesses. The ETPTA/EGMEA ratio of the acrylate mixture was varied from 10/0 to 1/9.

The anode active material particles were encapsulated into a core-shell structure using an air suspension coating method. The powder of core-shell microparticles with a reactive mass of ETPTA/EGMEA/HMPP was then exposed to UV radiation for 20 seconds. UV polymerization/crosslinking was carried out using a mercury UV lamp (100 W) with a radiation peak intensity of approximately 2000 mW/cm ² on the surface of the powder sample.

The above procedure produced S-based microparticles consisting of various S-conducting material particles encapsulated with a cross-linked ETPTA/EGMEA polymer shell. Also, for comparison purposes, unprotected S conductive material particles and conductive material particles protected with a carbon coating (without high modulus polymer encapsulation) were prepared and implemented in separate lithium-sulfur cells.

Example 5: Effect of lithium ion conductive additives on the lithium ion conductivity of high modulus polymers A wide variety of lithium ion conductive additives were used to prepare encapsulation shell materials to protect the core particles of anode active materials. The agents were added to several different polymeric matrix materials (Table 1). We have discovered that these polymer composites are suitable encapsulation shell materials if their lithium ion conductivity at room temperature is greater than or equal to 10 ⁻⁶ S/cm. In these materials, lithium ions appear to be able to easily diffuse into and out of the encapsulation shell with a thickness of 1 μm or less. For thick shells (eg 10 μm), a lithium ion conductivity of 10 ⁻⁴ S/cm or higher is required at room temperature.

Example 6: Mixing of sulfur and carbon/graphite particles by ball milling to form sulfur-containing particles Sulfur particles and particles of soft carbon (i.e., graphitizable disordered carbon), natural graphite, mesophase carbon, expanded graphite flakes , carbon nanofibers, and graphene sheets (0% to 95% by weight of S in the resulting composite) are physically blended and then ball milled for 2 to 24 hours to form S-containing composite particles (typically (shaped like a ball or potato). Particles with a typical size of 1-10 μm containing various S contents were then wrapped in a thin layer of high modulus polymer. A portion of the obtained fine particles was then formed into a cathode layer.

Example 7: Simple Sulfur Melt or Liquid Solution Mixing One way to combine sulfur with conductive materials (eg, carbon/graphite particles) is to use a solution or melt mixing process. Highly porous activated carbon particles, chemically etched mesocarbon microballs (activated MCMB), and exfoliated graphite worms were incubated at 177-120 °C (slightly above the melting point of S, 115.2 °C) for 10-60 min. Carbon particles impregnated with sulfur were obtained by mixing with sulfur melt.

Example 8: Preparation of sulfur-coated graphene sheet and its secondary particles (fine particles) This process involves generating elemental sulfur vapor and depositing S vapor on the surface of a single layer or several layers of graphene sheet. Accompany. Graphene sheets suspended in a liquid medium (eg, graphene oxide in water or graphene in NMP) were sprayed onto a substrate (eg, a glass surface) to form a thin layer of graphene sheets. This thin layer of graphene was then exposed to physical vapor deposition caused by sublimation. Although sublimation of solid sulfur occurs at temperatures above 40°C, significant practically useful sublimation rates typically do not occur until temperatures exceed 100°C. Typically, 117-160° C. with a deposition time of 10-120 minutes was used to deposit a thin film of sulfur on the graphene surface (sulfur thickness is approximately 1-10 nm). This thin layer of graphene with a thin film of sulfur deposited was then easily crushed into pieces of S-coated graphene sheets using an air jet mill. Some of these S-coated graphene sheets were directly wrapped in high modulus polymer. Some of these sheets were made into secondary particles of about 5-15 μm in diameter (eg, by spray drying) and then encapsulated with a high modulus polymer.

Example 9: Electrochemical impregnation of S into various porous carbon/graphite particles Electrochemical impregnation of S into the pores of activated carbon fibers, activated carbon nanotubes, and activated artificial graphite particles This was carried out by agglomerating the particles/fibers into a loosely packed layer. In this approach, an anode, an electrolyte, and a layer of such a loosely packed structure (which functions as a cathode layer) are placed in an outer container outside the lithium-sulfur cell. The equipment required is similar to electroplating systems well known in the art.

In a typical procedure, a metal polysulfide (M _x S _y ) is dissolved in a solvent (eg, a mixture of DOL/DME in a volume ratio of 1:3 to 3:1) to form an electrolyte solution. Optionally, an amount of lithium salt may be added, but this is not necessary for external electrochemical deposition. A wide variety of solvents are available for this purpose and there is no theoretical limit as to what type of solvent can be used. Any solvent can be used provided there is some solubility of the metal polysulfide in the desired solvent. Greater solubility means that more sulfur can be extracted from the electrolyte.

The electrolyte is then injected into a chamber or reactor under a dry, controlled atmosphere (eg, He or nitrogen gas). A metal foil can be used as the anode and a layer of porous structure as the cathode, both immersed in an electrolyte. This configuration constitutes an electrochemical impregnation and deposition system. The step of electrochemically impregnating the pores with sulfur is carried out at a current density ranging from 1 mA/g to 10 A/g, based on the layer weight of porous carbon/graphite particles/fibers.

The chemical reaction that takes place in this reactor can be represented by the following equation: M _x S _y →M _x S _y−z +zS (typically z=1-4). The thickness or particle size of the sulfur coating and the amount of S coating/particles impregnated can be controlled by the electrochemical reaction current density, temperature and time. Typically, the lower the current density and reaction temperature, the more uniform the S impregnation will be and the easier the reaction will be to control. As the reaction time increases, a large amount of S saturates within the pores. Additionally, electrochemical methods can rapidly convert impregnated S into metal polysulfides, such as polysulfide, sodium polysulfide, and potassium polysulfide.

Example 10: Chemical Reaction-Induced Sulfur Impregnation Herein, a chemical impregnation method is utilized to prepare chemically activated S-impregnated carbon fibers. The procedure started by adding 0.58 g of Na ₂ S to a flask filled with 25 ml of distilled water to form a Na ₂ S solution. Then, 0.72 g of S element was suspended in the Na ₂ S solution and stirred with a magnetic stirrer at room temperature for about 2 hours. The color of the solution slowly changed to orange-yellow as the sulfur dissolved. After dissolving the sulfur, a sodium polysulfide (Na ₂ S _x ) solution was obtained (x=4-10).

Then, sulfur-impregnated carbon fiber samples were prepared by chemical impregnation method with aqueous solution. First, 180 mg of expanded carbon fibers were suspended in 180 ml of ultrapure water with surfactant and then sonicated at 50° C. for 5 hours to form a stable carbon fiber dispersion. Then, a Na ₂ S x solution was added to the dispersion prepared as above in the presence of 5% _by weight of the surfactant cetyltrimethylammonium bromide (CTAB) to form a carbon fiber/Na ₂ S _x mixture after the preparation. The solution was sonicated for an additional 2 hours, then titrated with 100 ml of 2 mol/L HCOOH solution at a rate of 30-40 drops/min and stirred for 2 hours. Finally, the precipitate was filtered and washed several times with acetone and distilled water to remove salts and impurities. After filtration, the precipitate was dried in a drying oven at 50° C. for 48 hours. This reaction can be represented by the reaction: S _x ^2- +2H ⁺ → (x-1)S+H ₂ S.

Example 11: Sulfur impregnation induced by redox chemistry in activated MCMB and activated needle coke This chemistry-based deposition process uses sodium thiosulfate (Na ₂ S ₂ O ₃ ) as the sulfur source, Hydrochloric acid was used as the substance. An activated MCMB-water or activated needle coke-water suspension was prepared and then the two reactants (hydrochloric acid and Na ₂ S ₂ O ₃ ) were poured into this suspension. The reaction was allowed to proceed for 1-3 hours at 25-75°C to impregnate S into the pores of the activated structure. This reaction can be represented by _the following reaction: 2HCl+ _Na2S2O3 →2NaCl+S↓+ _SO2 ↑ _{+ H2O}

Example 12: Cycling Stability of Various Rechargeable Lithium Battery Cells Several series of Li metal sulfur and Li ion sulfur cells were prepared using the cathode layer prepared herein. The first series is Li metal cells containing copper foil as anode current collector, and the second series is Li metal cells containing nanostructured anodes of conductive filaments (based on electrospun carbon fibers or CNFs). It is a cell. The third series is Li-ion cells with a conductive filament nanostructured anode (based on electrospun carbon fibers coated with a thin layer of Si using CVD) and a copper foil current collector. The fourth series is Li-ion cells with an anode active material based on prelithiated graphite, as an example of a more common anode. After numerous charge/discharge cycles, cells containing nanostructured anodes were found to be essentially dendrite-free.

Charge storage capacity was measured periodically and recorded as a function of cycle number. The specific discharge capacity referred to herein is the total charge inserted into the cathode during discharge per unit mass of the composite cathode (cathode active material, conductive additive or support, binder, and any (Count combined weight with selected additives). Specific charge capacity refers to the amount of charge per unit mass of the composite cathode. The specific energy and specific power values shown in this section are based on total cell weight. Using both transmission electron microscopy (TEM) and scanning electron microscopy (SEM), morphological or microstructural changes in selected samples are observed after the desired number of charge and recharge cycles. It was done.

The cycling behavior of the three cells prepared in Example 4 is shown in Figure 8, indicating that high modulus polymer encapsulation of S-based particles, with or without carbon coating, provides the most stable cycling response. There is. Carbon coating alone does not help significantly improve cycle stability.

The cycling behavior of the two Li-S cells prepared in Example 2 is shown in FIG. One cell has a cathode containing microparticles of sulfur-CNT composite balls encapsulated in a cross-linked PVA-CN polymer, and the other cell has a cathode containing microparticles of unprotected sulfur-CNT composite balls. High modulus polymers imparted cycling stability to Li-S cells in the most dramatic way.

Figure 10 shows the cycling behavior of two room temperature Na-S cells. One cell has a cathode containing microparticles of sulfur-MCMB (activated) composite particles encapsulated with a cross-linked ETPTA polymer, and the other cell has microparticles of unprotected sulfur-MCMB (activated) composite particles. has a cathode containing. Again, the high modulus polymer significantly improved the cycling stability of the Na-S cell.

The above cycling stability data clearly demonstrate that the shuttle effects commonly associated with Li-S or Na-S cells are significantly reduced or essentially eliminated by the high modulus polymer encapsulation approach of the present invention. Proven.

Figures 11 and 12 show that the presence of a highly modulus polymer surrounding the sulfur-based cathode is based on the idea that this polymer shell typically has less electronic conductivity than a carbon coating and less ionic conductivity than a liquid electrolyte. This shows that the energy density of the metal-sulfur cell is not compromised. In contrast, and contrary to expectations of materials scientists, the cell's energy density actually improves.

In the lithium battery industry, it is common to define the cycle life of a battery as the number of charge/discharge cycles at which the battery's capacity decays by 20%, based on the initial capacity measured after the necessary electrochemical formation. Table 2 below summarizes cycle life data for a wide range of cells comprising sulfur cathode particles encapsulated with high modulus polymers of the present invention versus other types of cathode active materials.

The following discussion can be made from the data in Table 2 and FIGS. 9-12.
1) With the approach of the present invention, Li-S, Na-S, and KS batteries can achieve high cycle stability or long cycle life.
2) The inventive approach also results in alkali metal-sulfur cells with exceptional energy and power densities. A high cell-level energy density of 605 Wh/kg was achieved in a Li-S cell with a cathode active material encapsulated in a high modulus polymer. Also, very surprisingly, this cell achieves a high power density of 2875 W/kg, which is 4-5 times higher than the typical power density of lithium ion batteries and of conventional Li-S batteries. This power density improvement is due to the fact that convertible Li-S batteries operate with several chemical reactions during charging/discharging, which typically results in very low power densities (typically <<500 W /kg) is very important.
3) Similar advantageous features are also observed in Na-S and KS cells. This is evidenced by Figure 12, which shows a Ragone plot (cell power density versus cell energy density) for four alkali metal-sulfur cells.

In summary, the present invention provides an innovative, versatile and surprisingly effective platform material technology that enables the design and manufacture of superior alkali metal-sulfur rechargeable batteries. Alkali metal-sulfur cells with cathode layers containing microparticles of sulfur conductive material hybrid particles encapsulated in highly elastic polymers have high cathode active material utilization, high specific capacity, high specific energy, high power density, and shuttle effects. exhibits little or no oxidation and long cycle life. If a nanostructured carbon filament web is implemented on the anode to support a lithium film (eg, foil), the problem of lithium dendrites is also suppressed or eliminated.

Claims (53)

A rechargeable alkali metal-sulfur cell selected from a lithium-sulfur cell, a sodium-sulfur cell, or a potassium-sulfur cell, the alkali metal-sulfur cell comprising:
(a) an anode active material layer and an optional anode current collector supporting the anode active material layer;
(b) a cathode active material layer and an optional cathode current collector supporting the cathode active material layer;
(c) an electrolyte having an optional porous separator layer in ion contact with the anode active material layer and the cathode active material layer;
and the cathode active material layer includes a plurality of fine particles of a sulfur-containing material selected from a sulfur-carbon hybrid, a conductive polymer-sulfur hybrid, a metal sulfide, a sulfur compound, or a combination thereof, and at least one of the fine particles One is a recoverable tensile strain of 10% to 700% when measured without additives or reinforcements, a lithium ion conductivity of 10 ⁻⁵ S/cm or more at room temperature, and a thickness of 0.5 nm to 10 μm. A lithium-sulfur, sodium-sulfur, or potassium-sulfur cell characterized in that it consists of one or more sulfur-containing material particles wrapped or encapsulated by a thin layer of highly elastic polymer having a Rechargeable alkali metal-sulfur cells selected from: The rechargeable alkali metal-sulfur cell of claim 1, wherein the sulfur-carbon hybrid or conductive polymer-sulfur hybrid is a mixture, blend, composite, or combination of sulfur or sulfide and carbon or conductive polymer material. A rechargeable alkali metal-sulfur cell, characterized in that it is a chemically or physically bonded object. 2. The rechargeable alkali metal-sulfur cell according to claim 1, wherein the highly elastic polymer has an ether bond, a nitrile-derived bond, a benzoyl peroxide-derived bond, an ethylene oxide bond, a propylene oxide bond, and a vinyl alcohol bond in the crosslinked network of the polymer chain. A rechargeable alkali metal-sulfur cell comprising said crosslinked network of polymer chains having bonds, cyano-resin bonds, triacrylate monomer-derived bonds, tetraacrylate monomer-derived bonds, or combinations thereof. 2. The rechargeable alkali metal-sulfur cell according to claim 1, wherein the highly elastic polymer includes a nitrile-containing polyvinyl alcohol chain, a cyano resin chain, a pentaerythritol tetraacrylate chain, a pentaerythritol triacrylate chain, and an ethoxylated trimethylolpropane triacrylate chain. A rechargeable alkali metal-sulfur cell characterized in that it comprises a crosslinked network of polymer chains selected from (ETPTA) chains, ethylene glycol methyl ether acrylate (EGMEA) chains, or combinations thereof. 2. The rechargeable alkali metal-sulfur cell of claim 1, wherein the metal sulfide comprises M _x S _y , x is an integer from 1 to 3, y is an integer from 1 to 10, and M is an alkali metal sulfide. A rechargeable alkali metal-sulfur cell characterized in that it is a metal element selected from a metal, an alkali metal selected from Mg or Ca, a transition metal, a metal from groups 13 to 17 of the periodic table, or a combination thereof. The rechargeable alkali metal-sulfur cell according to claim 5, characterized in that the metal element M is selected from Li, Na, K, Mg, Zn, Cu, Ti, Ni, Co, Fe, or Al. A rechargeable alkali metal-sulfur cell. The rechargeable alkali metal-sulfur cell according to claim 1, wherein the metal sulfide is Li ₂ S ₁ , Li ₂ S ₂ , Li ₂ S ₃ , Li ₂ S ₄ , Li ₂ S ₅ , Li ₂ S ₆ , _{Li2S7 , Li2S8 , Li2S9 , Li2S10 , Na2S1 , Na2S2 , Na2S3 , Na2S4 , Na2S5 , Na2S6 , Na2S7 , Na2S8 , Na2S9 , Na2S10 , K2S1 , K2S2 , K2S3 , K2S4 , K2S5 , K2S6 ,} A rechargeable alkali metal-sulfur cell comprising K ₂ S ₇ , K ₂ S ₈ , K ₂ S ₉ , or K ₂ S ₁₀ . The rechargeable alkali metal-sulfur cell according to claim 1, wherein the carbon material of the cathode active material layer is mesophase pitch, mesophase carbon, mesocarbon microbeads (MCMB), coke particles, expanded graphite flakes, artificial graphite particles. , natural graphite particles, highly oriented pyrolytic graphite, soft carbon particles, hard carbon particles, carbon nanotubes, carbon nanofibers, carbon fibers, graphite nanofibers, graphite fibers, carbonized polymer fibers, activated carbon, carbon black, or combinations thereof. A rechargeable alkali metal-sulfur cell characterized by being selected. The rechargeable alkali metal-sulfur cell of claim 1, wherein the carbon is pure graphene, graphene oxide, reduced graphene oxide (RGO), fluorinated graphene, nitrogenated graphene, hydrogenated graphene, doped graphene, A rechargeable alkali metal-sulfur cell characterized in that it is selected from functionalized graphene or a combination thereof. The rechargeable alkali metal-sulfur cell of claim 1, wherein the conductive polymer-sulfur hybrid is selected from polyaniline, polypyrrole, polythiophene, polyfuran, bicyclic polymers, sulfonated derivatives thereof, or combinations thereof. A rechargeable alkali metal-sulfur cell characterized in that it comprises an essentially electrically conductive polymer. The rechargeable alkali metal-sulfur cell of claim 1, wherein the high modulus polymer comprises 0.1% to 50% by weight of a lithium ion conductive additive dispersed therein; or carbon nanotubes; A rechargeable alkali metal-sulfur cell, characterized in that it contains therein 0.1% to 10% by weight of reinforcing nanofilaments selected from carbon nanofibers, graphene, or a combination thereof. The rechargeable alkali metal-sulfur cell of claim 1, wherein the high modulus polymer is mixed with a lithium ion conductive additive to form a composite, and the lithium ion conductive additive is mixed with the high modulus polymer. Li ₂ CO ₃ , Li ₂ O, Li ₂ C ₂ O ₄ , LiOH, LiX, ROCO ₂ Li, HCOLi, ROLi, (ROCO ₂ Li) ₂ , (CH ₂ OCO ₂ Li) ₂ , Li ₂ selected from S, Li _x SO _y , or a combination thereof, characterized in that X=F, Cl, I, or Br, R=hydrocarbon group, x=0-1, y=1-4 Rechargeable alkali metal-sulfur cell. The rechargeable alkali metal-sulfur cell of claim 1, wherein the high modulus polymer is mixed with a lithium ion conductive additive to form a composite, and the lithium ion conductive additive is mixed with the high modulus polymer. Lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and lithium trifluoromethanesulfonate (LiCF _{3 )} . SO ₃ ), lithium bis-trifluoromethylsulfonylimide (LiN(CF ₃ SO ₂ ) ₂ ), lithium bis(oxalato)borate (LiBOB), lithium oxalyl difluoroborate (LiBF ₂ C ₂ O ₄ ), lithium nitrate ( LiNO ₃ ), Li-fluoroalkyl-phosphoric acid (LiPF ₃ (CF ₂ CF ₃ ) ₃ ), lithium bisberfluoro-ethylsulfonylimide (LiBETI), lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl) A rechargeable alkali metal-sulfur cell, characterized in that the cell is selected from imide, lithium trifluoromethanesulfonimide (LiTFSI), ionic liquid lithium salt, or a combination thereof. The rechargeable alkali metal-sulfur cell of claim 1, wherein the highly elastic polymer is a conductive polymer selected from polyaniline, polypyrrole, polythiophene, polyfuran, bicyclic polymers, sulfonated derivatives thereof, or combinations thereof. A rechargeable alkali metal-sulfur cell characterized in that it is mixed with a polymer. The rechargeable alkali metal-sulfur cell of claim 1, wherein the highly elastic polymer is poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA). ), poly(vinylidene fluoride) (PVdF), polybis-methoxyethoxyethoxide-phosphazenex, polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), these A rechargeable alkali metal-sulfur cell characterized in that it forms a mixture or blend with a lithium ion conducting polymer selected from sulfonated derivatives or combinations thereof. The rechargeable alkali metal-sulfur cell according to claim 1, wherein the highly elastic polymer has a lithium ion conductivity of 10 ⁻⁵ S/cm to 5×10 ⁻² S/cm at room temperature. Rechargeable alkali metal-sulfur cell. The rechargeable alkali metal-sulfur cell of claim 1, wherein the electrolyte is a polymer electrolyte, a polymer gel electrolyte, a composite electrolyte, an ionic liquid electrolyte, a non-aqueous liquid electrolyte, a soft matter phase electrolyte, a solid electrolyte, or a combination thereof. A rechargeable alkali metal-sulfur cell characterized in that it is selected from: 2. The rechargeable alkali metal-sulfur cell of claim 1, wherein the electrolyte comprises lithium perchlorate ( _LiClO4 ), lithium hexafluorophosphate ( _LiPF6 ), lithium borofluoride ( _LiBF4 ), hexafluoride. Lithium arsenide (LiAsF ₆ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium bis-trifluoromethylsulfonylimide (LiN(CF ₃ SO ₂ ) ₂ ), lithium bis(oxalato)borate (LiBOB), Lithium oxalyl difluoroborate (LiBF ₂ C ₂ O ₄ ), lithium nitrate (LiNO ₃ ), Li-fluoroalkyl-phosphate (LiPF ₃ (CF ₂ CF ₃ ) ₃ ), lithium bisperfluoroethylsulfonylimide (LiBETI), Ionic liquid salts, sodium perchlorate (NaClO ₄ ), potassium perchlorate (KClO ₄ ), sodium hexafluorophosphate (NaPF ₆ ), potassium hexafluorophosphate (KPF ₆ ), sodium borofluoride (NaBF ₄ ), Potassium borofluoride (KBF ₄ ), sodium hexafluoroarsenide, potassium hexafluoroarsenide, sodium trifluorometasulfonate (NaCF ₃ SO ₃ ), potassium trifluoromethanesulfonate (KCF ₃ SO ₃ ), bis-trifluoro selected from sodium methylsulfonylimide (NaN(CF ₃ SO ₂ ) ₂ ), sodium trifluoromethanesulfonimide (NaTFSI), and potassium bis-trifluoromethylsulfonylimide (KN(CF ₃ SO ₂ ) ₂ ), or combinations thereof A rechargeable alkali metal-sulfur cell characterized by: 19. The rechargeable alkali metal-sulfur cell according to claim 18, wherein the electrolyte solvent is ethylene carbonate (EC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), ethyl propionate, Methyl propionate, propylene carbonate (PC), γ-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, xylene or methyl acetate (MA) ), fluoroethylene carbonate (FEC), vinylene carbonate (VC), allylethyl carbonate (AEC), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), tetraethylene glycol dimethyl ether (TEGDME), poly( a rechargeable alkali metal selected from ethylene glycol dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DEGDBE), 2-ethoxyethyl ether (EEE), sulfone, sulfolane, room temperature ionic liquid, or combinations thereof. sulfur cell. The rechargeable alkali metal-sulfur cell according to claim 1, wherein the anode active material layer comprises lithium metal, sodium metal, potassium metal, lithium metal alloy, sodium metal alloy, potassium metal alloy, lithium intercalation compound, sodium intercalation compound, potassium intercalation compound, lithiated compound, sodated compound, potassium doped compound, lithiated titanium dioxide, lithium titanate, lithium manganate, lithium transition metal oxide, Li ₄ Ti ₅ O ₁₂ , or a combination thereof. The rechargeable alkali metal-sulfur cell of claim 1, wherein the cell is a lithium ion-sulfur cell, and the anode active material layer comprises:
(a) Silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), nickel (Ni), cobalt ( Co), manganese (Mn), titanium (Ti), iron (Fe), and cadmium (Cd), and lithiated versions thereof,
(b) Alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, or Cd with other elements, and lithiated versions thereof, said alloys or compounds being stoichiometric or non-stoichiometric;
(c) Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ni, Co, Ti, Mn, or Cd oxide, carbide, nitride, sulfide, phosphide, selenide, and tellurides, as well as mixtures or complexes thereof, and lithiated versions thereof,
(d) Sn salts and hydroxides and lithiated versions thereof;
(e) A rechargeable alkali metal-sulfur cell characterized in that it comprises an anode active material selected from the group consisting of carbon materials and prelithiated versions thereof, and combinations thereof. The rechargeable alkali metal-sulfur cell according to claim 1, wherein the cell is a sodium ion-sulfur cell or a potassium ion-sulfur cell, and the anode active material layer comprises:
(a) Silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), titanium doped with sodium or potassium (Ti), cobalt (Co), nickel (Ni), manganese (Mn), cadmium (Cd), and mixtures thereof,
(b) sodium- or potassium-containing alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof;
(c) Sodium- or potassium-containing oxides, carbides, and nitrides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or complexes thereof. , sulfide, phosphide, selenide, telluride, or antimonide,
(d) sodium or potassium salts;
A rechargeable alkali metal-sulfur cell characterized in that it comprises an anode active material selected from the group consisting of (e) hard carbon or soft carbon particles, and presodiumized versions thereof, and (f) combinations thereof. The rechargeable alkali metal-sulfur cell of claim 1, wherein the particulates are 80% to 99% by weight based on the combined total weight of the high modulus polymer and the sulfur, metal sulfide, or metal compound. A rechargeable alkali metal-sulfur cell, characterized in that it contains sulfur, a metal sulfide, or a metal compound. A cathode active material layer in a rechargeable alkali metal-sulfur cell, the cathode active material layer comprising sulfur selected from sulfur-carbon hybrids, conductive polymer-sulfur hybrids, metal sulfides, sulfur compounds, or combinations thereof. comprising a plurality of microparticles of a containing material, at least one of said particles having a recoverable tensile strain of 10% or more when measured without additives or reinforcement, lithium ion of 10 ⁻⁵ S/cm or more at room temperature. Rechargeable, characterized in that it consists of one or more sulfur-containing material particles completely surrounded or encapsulated by a thin layer of highly elastic polymer having a conductivity and a thickness of 0.5 nm to 10 μm. Cathode active material layer in an alkali metal-sulfur cell. In the cathode active material layer of claim 24, the sulfur-carbon hybrid or conductive polymer-sulfur hybrid is a mixture, blend, composite, or chemical combination of sulfur or sulfide and carbon or conductive polymer material. Or a cathode active material layer characterized in that it is a physically bonded object. In the cathode active material layer according to claim 24, the highly elastic polymer has ether bonds, nitrile-derived bonds, benzoyl peroxide-derived bonds, ethylene oxide bonds, propylene oxide bonds, vinyl alcohol bonds, and cyano bonds in the crosslinked network of polymer chains. - A cathode active material layer comprising the crosslinked network of polymer chains having resin bonds, bonds derived from triacrylate monomers, bonds derived from tetraacrylate monomers, or combinations thereof. In the cathode active material layer according to claim 24, the highly elastic polymer includes a nitrile-containing polyvinyl alcohol chain, a cyano resin chain, a pentaerythritol tetraacrylate chain, a pentaerythritol triacrylate chain, and ethoxylated trimethylolpropane triacrylate (ETPTA). A cathode active material layer comprising a crosslinked network of polymer chains selected from ethylene glycol methyl ether acrylate (EGMEA) chains, or combinations thereof. In the cathode active material layer according to claim 24, the metal sulfide includes M _x S _y , x is an integer of 1 to 3, y is an integer of 1 to 10, and M is an alkali metal, Mg or Ca, a transition metal, a metal from groups 13 to 17 of the periodic table, or a combination thereof. In the cathode active material layer according to claim 24, the carbon material of the cathode active material layer is mesophase pitch, mesophase carbon, mesocarbon microbeads (MCMB), coke particles, expanded graphite flakes, artificial graphite particles, natural graphite. particles, highly oriented pyrolytic graphite, soft carbon particles, hard carbon particles, carbon nanotubes, carbon nanofibers, carbon fibers, graphite nanofibers, graphite fibers, carbonized polymer fibers, activated carbon, carbon black, or combinations thereof. A cathode active material layer characterized by: In the cathode active material layer according to claim 24, the metal sulfide may include M _x S _y , x is an integer from 1 to 3, y is an integer from 1 to 10, and M is an alkali metal, A cathode active material layer comprising a metal element selected from an alkali metal selected from Mg or Ca, a transition metal, a metal from groups 13 to 17 of the periodic table, or a combination thereof. The cathode active material layer according to claim 24, further comprising a binder resin that binds the plurality of fine particles together to form the cathode active material layer, and the binder resin is not part of the plurality of fine particles. A cathode active material layer, which is located outside the plurality of fine particles. A cathode active material layer in a rechargeable alkali metal-sulfur cell, the cathode active material layer comprising a resin binder, an optional conductive additive, and a sulfur-carbon hybrid, a conductive polymer-sulfur hybrid, a metal sulfide, a plurality of particles of a sulfur-containing material selected from sulfur compounds, or combinations thereof, wherein the sulfur-containing material particles are bound by the resin binder to form an integrated solid layer, and the integrated solid layer comprises an additive. or a thin layer of highly elastic polymer with a recoverable tensile strain of 10% or more when measured without reinforcement, a lithium ion conductivity of 10 ⁻⁵ S/cm or more at room temperature, and a thickness of 0.5 nm to 10 μm. A cathode active material layer in a rechargeable alkali metal-sulfur cell characterized in that it is covered and protected by a layer. 33. The cathode active material layer of claim 32, wherein the integrated solid layer is bonded to a cathode current collector by the resin binder. A rechargeable alkali metal-sulfur cell selected from a lithium-sulfur cell, a sodium-sulfur cell, or a potassium-sulfur cell, the alkali metal-sulfur cell comprising: (a) an anode active material layer and the anode active material. an optional anode current collector supporting the layer; (b) a cathode comprising the cathode active material layer of claim 33; and (c) an optional anode current collector in ionic contact with the anode active material layer and the cathode active material layer. an electrolyte with a selected porous separator layer. A powder mass in the cathode of a lithium-sulfur battery, said powder mass comprising a plurality of sulfur-containing materials selected from sulfur-carbon hybrids, conductive polymer-sulfur hybrids, metal sulfides, sulfur compounds, or combinations thereof. microparticles, at least one of the microparticles having a recoverable tensile strain of 10% or more when measured without additives or reinforcements, a lithium ion conductivity of 10 ⁻⁵ S/cm or more at room temperature, and 0. Powder mass in the cathode of a lithium-sulfur battery, characterized in that it consists of one or more sulfur-containing material particles wrapped or encapsulated by a thin layer of highly elastic polymer with a thickness of .5 nm to 10 μm. . 36. The powder mass of claim 35, wherein the sulfur-carbon hybrid or conductive polymer-sulfur hybrid is a mixture, blend, composite, chemical or physical combination of sulfur or sulfide and carbon or conductive polymer material. A powder lump characterized by being an object bound to. 36. The powder mass according to claim 35, wherein the highly elastic polymer has ether bonds, nitrile-derived bonds, benzoyl peroxide-derived bonds, ethylene oxide bonds, propylene oxide bonds, vinyl alcohol bonds, and cyano-resin bonds in the crosslinked network of polymer chains. A powder mass comprising said crosslinked network of polymer chains having bonds, bonds derived from triacrylate monomers, bonds derived from tetraacrylate monomers, or combinations thereof. 36. The powder mass according to claim 35, wherein the highly elastic polymer comprises a nitrile-containing polyvinyl alcohol chain, a cyano resin chain, a pentaerythritol tetraacrylate chain, a pentaerythritol triacrylate chain, an ethoxylated trimethylolpropane triacrylate (ETPTA) chain, A powder mass characterized in that it comprises a crosslinked network of polymer chains selected from ethylene glycol methyl ether acrylate (EGMEA) chains or combinations thereof. 36. The powder mass according to claim 35, wherein the metal sulfide comprises M _x S _y , x is an integer from 1 to 3, y is an integer from 1 to 10, and M is an alkali metal, Mg or Ca. A powder lump characterized in that it is a metal element selected from an alkali metal selected from, a transition metal, a metal from groups 13 to 17 of the periodic table, or a combination thereof. A method of manufacturing a rechargeable alkali metal-sulfur cell according to claim 1, the method comprising:
(a) providing a cathode and an optional cathode current collector supporting the cathode;
(b) providing an alkali metal anode selected from Li, Na, K, or combinations thereof and an optional anode current collector supporting said anode;
(c) providing an electrolyte in contact with the anode and the cathode, and an optional separator electrically separating the anode and the cathode;
, the cathode comprising a plurality of microparticles of a sulfur-containing material, at least one of the microparticles having a recoverable tensile strain of 10% or more when measured without additives or reinforcements, 10 ^- at room temperature. consisting of one or more sulfur-containing material particles wrapped or encapsulated by a thin layer of highly elastic polymer with a lithium ion conductivity of ⁵ S/cm or more and a thickness of 0.5 nm to 10 μm A method of manufacturing a rechargeable alkali metal-sulfur cell characterized by: 41. The method of claim 40, wherein the sulfur-containing material is selected from sulfur-carbon hybrids, conductive polymer-sulfur hybrids, metal sulfides, sulfur compounds, or combinations thereof. 42. The method of claim 41, wherein the sulfur-carbon hybrid or conductive polymer-sulfur hybrid is a mixture, blend, composite, chemical or physical combination of sulfur or sulfide and carbon or conductive polymer material. A manufacturing method characterized in that the object is bonded to. In the manufacturing method according to claim 40, the highly elastic polymer has an ether bond, a nitrile-derived bond, a benzoyl peroxide-derived bond, an ethylene oxide bond, a propylene oxide bond, a vinyl alcohol bond, and a cyano resin in the crosslinked network of the polymer chain. A method of manufacturing comprising the crosslinked network of polymer chains having bonds, bonds derived from triacrylate monomers, bonds derived from tetraacrylate monomers, or combinations thereof. In the manufacturing method according to claim 40, the highly elastic polymer comprises a nitrile-containing polyvinyl alcohol chain, a cyano resin chain, a pentaerythritol tetraacrylate chain, a pentaerythritol triacrylate chain, an ethoxylated trimethylolpropane triacrylate (ETPTA) chain, A manufacturing method characterized in that it comprises a crosslinked network of polymer chains selected from ethylene glycol methyl ether acrylate (EGMEA) chains or combinations thereof. 41. The manufacturing method according to claim 40, wherein the highly elastic polymer has a thickness of 1 nm to 100 nm. 41. The manufacturing method according to claim 40, wherein the highly elastic polymer has a lithium ion conductivity of 1×10 ⁻⁵ S/cm to 5×10 ⁻² S/cm. 41. The method of claim 40, wherein the high modulus polymer has a recoverable tensile strain of 30% to 300%. 41. The manufacturing method according to claim 40, wherein the plurality of fine particles are produced by pan coating, air suspension, centrifugal extrusion, vibrating nozzle, spray drying, ultrasonic atomization, coacervation phase separation, interfacial polycondensation, in situ polymerization, matrix A manufacturing method characterized in that it consists of particles of sulfur-containing material that are wrapped or encapsulated by a thin layer of said highly elastic polymer using a procedure selected from polymerization, or a combination thereof. 41. The method of claim 40, wherein the plurality of microparticles are encapsulated or encapsulated by a mixture of the highly elastic polymer with an elastomer, a conductive polymer, a lithium ion conductive material, a reinforcing material, or a combination thereof. A manufacturing method comprising particles of a sulfur-containing material. 50. The method of claim 49, _{wherein the} lithium ion _conductive material is dispersed in the high modulus polymer and comprises _Li2CO3 , _Li2O , _Li2C2O4 , LiOH, _LiX , _ROCO2Li. , HCOLi, ROLi, ( _{ROCO2Li ) 2} , ( _CH2OCO2Li ) ₂ , _Li2S , _LixSOy , or a combination thereof, and _X =F, Cl, I, or Br, R = hydrocarbon group, x = 0 to 1, and y = 1 to 4. 50. The manufacturing method according to claim 49, wherein the lithium ion conductive material is dispersed in the highly elastic polymer and comprises lithium perchlorate ( _LiClO4 ), lithium hexafluorophosphate ( _LiPF6 ), lithium borofluoride (LiBF). ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium bis-trifluoromethylsulfonylimide (LiN(CF ₃ SO ₂ ) ₂ ), lithium bis(oxalato) Borate (LiBOB), lithium oxalyl difluoroborate (LiBF ₂ C ₂ O ₄ ), lithium nitrate (LiNO ₃ ), Li-fluoroalkyl-phosphoric acid (LiPF ₃ (CF ₂ CF ₃ ) ₃ ), lithium bisberfluoro- selected from ethylsulfonylimide (LiBETI), lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonimide (LiTFSI), ionic liquid-based lithium salt, or a combination thereof. manufacturing method. A method of manufacturing a rechargeable alkali metal-sulfur cell selected from a lithium-sulfur cell, a sodium-sulfur cell, or a potassium-sulfur cell, the method comprising: (a) an anode active material layer and the anode active material layer; (b) providing a cathode comprising an optional anode current collector supporting layer; (b) providing a cathode comprising a cathode active material layer according to claim 32; and (c) said anode active material layer. and providing an electrolyte with an optional porous separator layer in ionic contact with the cathode active material layer; (d) combining the anode, the cathode, and the electrolyte to form a battery unit; a rechargeable alkali metal-sulfur cell selected from a lithium-sulfur cell, a sodium-sulfur cell, or a potassium-sulfur cell. Method of manufacturing sulfur cells. A method of manufacturing a rechargeable alkali metal-sulfur cell selected from a lithium-sulfur cell, a sodium-sulfur cell, or a potassium-sulfur cell, the method comprising: (a) an anode active material layer and the anode active material layer; (b) providing an anode comprising an optional anode current collector supporting layer; (b) providing a cathode comprising a layer of cathode active material optionally supported by a cathode current collector; and (c) (d) providing a porous separator layer and an electrolyte in ion contact with the anode active material layer and the cathode active material layer; and (d) a layer of high modulus polymer between the cathode active material layer and the porous separator layer. the highly modulus polymer has a recoverable tensile strain of greater than or equal to 10% when measured without additives or reinforcement, a lithium ion conductivity of greater than or equal to 10 ⁻⁵ S/cm at room temperature, and A method for producing a rechargeable alkali metal-sulfur cell selected from a lithium-sulfur cell, a sodium-sulfur cell, or a potassium-sulfur cell, characterized in that it has a thickness of 0.5 nm to 10 μm.

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